So, you've been playing "Pokémon GO" and you've crested level five. Congrats! You can now join one of the three teams in the game (GO TEAM VALOR WOOOOO!) and start battling in gyms. This is, in so many words, where the real game begins. 

So, uh, how do you battle? What do those gym levels mean? And what happens when you go to a gym that's part of your team? 

We've got answers to all that and more!

SEE ALSO: The Pokémon Go peak is over, but the game is still on top

First things first: Locate your local gym.

If you've spent any time playing "Pokémon Go," you've almost certainly seen your local gym. Gyms are crucial in the world of Pokémon, because they're where trainers (players) go to train their Pokémon. In the world of "Pokémon Go," they're just as crucial for the same reason.

There is, of course, a twist: In "Pokémon Go" you choose one of three teams (Valor, Instinct, or Mystic), which is tied to the gyms you take over. If you see a greyed out gym on your "Pokémon GO" map, that's an unclaimed gym that you can simply walk up to (in real life) that you can then claim for whatever team you belong to.

But, at this point, most gyms are claimed.

Go to a friendly gym to practice battling Pokémon before the real thing.

Don't waste your precious time fighting Pokémon that you can't beat. If your best Pokémon has a lower CP rating (combat power — we'll explain more later), you'll almost certainly lose the fight. Train up your Pokémon first by going to a gym that your team already owns and competing in friendly battles. You'll learn the ins and outs of battling and get something from it (XP for leveling up). Huzzah!

As a bonus, your team gets "Prestige" from your battle, which is how gyms become higher level. In so many words, by taking on friendly matches at a gym your team already controls, you're making that gym even stronger against future attacks from rival teams!

Review the gym: Know what you're getting into.

So, you've walked to a gym and you're thinking about battling. Great! Now what do all these stats and numbers and stuff mean?

"World of Warcraft" has made a genuine cultural impact since its launch in 2004, inspiring everything from a "South Park" episode to the recently-released Hollywood movie adaptation. But there are still countless people who have never played the smash-hit online game.

With its next expansion, "World of Warcraft: Legion," set to launch on August 30, you might be wondering: should I jump in? What's so great about this game that people have been playing for 12 years? 

Here are just a few of the reasons why "World of Warcraft" is so huge:

SEE ALSO: 5 reasons why people love 'Metal Gear Solid'

It took one of the most hardcore genres around and made it accessible

In case you weren't sure, "World of Warcraft" is a massively multiplayer online role-playing game, or MMORPG for short. That means it takes place in a huge, persistent world where players run around and do quests with each other, level up, collect loot and maybe even fight each other.

Before "World of Warcraft" came along, the most popular MMORPGs were games like "EverQuest," which were not especially welcoming to new players, comparatively. It was a different time, so expectations were different.

"World of Warcraft" did a better job of explaining the more arcane aspects of the genre and easing newcomers in, even if it wasn't perfect. It's actually a much more friendly game now than it was at launch, too. This is a great time to jump in.

Its world is enormous, varied, and a joy to explore — and it keeps evolving

The original release of the game had two gigantic continents for players to explore, all based on the "Warcraft" series of computer strategy games. Each of its numerous expansion packs has added another sizable landmass, meaning there's a whole lot to see out there.

The "Warcraft" fantasy universe draws inspiration from pretty much every other fantasy universe, so there's a ton of variety around every corner. One playable race lives in a huge, crashed spaceship, while another is a race of zombies that lives in the sewers underneath an abandoned city.

There are also intelligent, bipedal cows and martial artist pandas to go along with your generic humans and orcs. The game's stellar art direction helps bring all of these different races and their respective homelands to life.

It's designed to be as addictive as possible

"World of Warcraft" requires a paid subscription to play, meaning it's designed to keep you playing as long as possible. That may sound like a negative thing, but it's just honesty, and they do it very well.

From the minute you start playing, the game constantly dangles a carrot on a stick in front of you. It could be a new ability, a powerful sword, or a cool mechanical chicken to ride on.

Whatever it is, it's always just attainable enough that you'll say "just one more quest before bed!" Before you know it, it's 3:00 in the morning. That's how "World of Warcraft" goes.

If you are fearful of nation-states tracking your every move or corporate spies activating your phone's microphone in a meeting, there's a phone case built just for you.

Amid a huge number of cybersecurity companies pitching their wares at the Black Hat security conference last week in Las Vegas, one was offering a product geared toward CEOs and government officials — or the ultraparanoid.

The company is called Privoro, and the case is the Privacy Guard.

Here's what it's like:

SEE ALSO: Hackers show how they tricked a Tesla into hitting objects in its path

We dodged the huge crowds at Black Hat to check out Privoro's Privacy Guard, which claims to make eavesdropping on your smartphone impossible.

When it's all put together, this is what the Privacy Guard looks like. It can be configured to be ultra-private like this, with a Faraday cage shell that blocks all signals from going in or out ...

... or like this, with covers that slide over the top and bottom of your phone. These covers block the cameras and segregate the iPhone charging slot, keeping a user from getting hacked through an exploit of the Lightning port.

When walking up to the salad bar, it's often a struggle to decide which leafy greens to put in next to your croutons and tasty dressing.

Is there a type of lettuce that ranks above the rest, as far as nutrition goes? 

We've got you covered. Drawing from the CDC's rankings of "powerhouse foods," as well as the nutritional breakdowns of the veggies, we compiled the best, most nutritional greens for your salads, ranked from worst to best. The more nutrition packed in per calorie, the better the vegetable ranked on the list. 

Here's the rundown. 

SEE ALSO: Not all condiments are created equal — here are the best and worst ones for you

DON'T MISS: RANKED: These are the healthiest grains for you

10. Iceberg lettuce

9. Arugula

8. Kale

At the end of the day, your likability often boils down to your emotional intelligence.

You might be naturally likable, or you might be a work in progress. If you're in the latter group, here are the highlights of one particularly helpful Quora thread: "What are useful social skills that can be picked up quickly?"

Out of the 83 answers submitted by users, we selected 18 simple ways to instantly become more likable:

Kathleen Elkins and Natalie Walters contributed to previous versions of this article.

SEE ALSO: 14 habits of the most likable people

1. Make eye contact

"It is an idiotically simple thing, but it remains one of the most impactful life hacks around,"writes Quora user Brad Porter. "The most attractive quality in a person is confidence. But 'be confident' is not very good advice. Instead, find the best proxy for confidence, in terms of interactive behavior. And that's eye contact."

Start this habit immediately, says Porter. It requires no practice or special skill — just the commitment to meet someone's gaze and look them in the eye while conversing.

2. Put your smartphone in your pocket

And keep it there until your conversation or meeting is over. Basil Chiasson puts it simply: "Pay attention. Look at them. Stop what you're doing. No interruptions."

This is another simple yet effective habit that can be executed immediately and does not require any effort or skill.

3. Call people by name

The next time someone greets you by name or uses your name mid-conversation, remember how great that feels.

If you have trouble putting names to faces, try different strategies, such as writing them down or using imagery or rhymes associated with the name. Quora user Howard Lee suggests repeating names verbally when you're first introduced and then twice more in your head.

US gas prices have hit their lowest point in recent history, falling to levels last seen before the Great Recession. According to The New York Times, the national average fell to $2.18 a gallon in July.

Since gas prices are linked to the American road trip, comparing how far a tank will get you on US highways is a useful measure for prices at the pump.

The cost-information website How Much, with an assist from SVM, put together some vividly colored maps to illustrate how far $50 worth of gas would take you from major US cities, based on the average gas prices in June for the years 2005, 2008, 2011, 2014, 2015, and 2016 and assuming that your car gets 24 miles a gallon.

Summer road-trip season is wrapping up, so check out how far you can go below.

SEE ALSO: These maps show how dangerous illegal drugs flow around the globe

New York City

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Los Angeles

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How much does it take to buy a home?

Mortgage site HSH.com has updated its estimate of how much annual income a household would need to buy a home in major metropolitan areas in the US, according to second-quarter 2016 data.

In Q2, mortgage rates fell across the board, while list prices in major metros such as Chicago and San Francisco increased dramatically — 18% and 15%, respectively.

HSH.com looked at median home prices from the National Association of Realtors. It took into account interest rates for common 30-year fixed-rate mortgages and property taxes and insurance costs to figure out how much money it would take to pay a median-priced home's mortgage, taxes, and insurance in each city, and how much you'd have to earn to afford it.

HSH.com emphasizes that this is only the base cost of owning a home, without taking into account maintenance and other incidentals.

The site also calculated how it would change the salary needed to buy a home if a buyer were to put 10% down instead of the recommended 20%. No matter where you are, putting down less makes things more expensive — you can visit HSH.com to see both numbers.

Salaries are listed from lowest to highest needed and are rounded to the nearest $500.

SEE ALSO: Here's how much you need to earn to live comfortably in 15 major US cities while still saving money

19. San Antonio

Population: 1,409,000

Median home price: $210,500

Monthly mortgage payment: $1,137

Salary needed to buy: $47,000

18. Orlando

Population: 255,483

Median home price: $223,000

Monthly mortgage payment: $1,152

Salary needed to buy: $49,500

17. Minneapolis

Population: 407,207

Median home price: $242,400

Monthly mortgage payment: $1,208

Salary needed to buy: $52,000

With Chipotle fumbling lately, the fast-casual Tex Mex sector is shaken.

But in New York City there's a chain that could steal the limelight.

Dos Toros, founded in 2009 by brothers Leo and Oliver Kremer, is looking to carve out a chunk of the market.

The New York City chain is self-funded – no outside investors or nest eggs, just a business loan and family and friends— and reported to be on track to earn $20 million in 2015.

And considering its popularity, the brothers are looking to expand elsewhere as soon as possible. "We can open five a year for the next five years, and move to multiple cities," Leo told Entrepreneur.

With 11 locations in Brooklyn and Manhattan and plans to saturate Midtown, Dos Toros seems unstoppable.

I decided to head to the nearest one to see why this local chain is exploding, and to find out if it can survive elsewhere in a pretty competitive Mexican fast-casual market.

It's a brisk evening — perfect to warm up with some Tex-Mex food at this Dos Toros on 23rd Street and Park Avenue.

The interior feels cozy and rich with vibrant red walls and natural wood everywhere.

I'm hungry, so I step right up for my order. I'll choose a chicken plato — their name for a burrito bowl — and a steak quesadilla.

Your 20s see you through from your awkward teenage years to your transformation into a full-fledged adult. The decade is all about experiencing new things, taking on new challenges, making mistakes and learning from them, and working towards becoming the person you're meant to be. For those reasons, there's no better time than your 20s to ditch bad health habits and get on to being that better you.

Habits form from routine behaviors, and they're most easily broken while you're still growing and malleable. While you're in your 20s figuring out just what kind of life you want to lead — from big career decisions to relationships to yourself — it's a good time to establish the kind of behavior you'll want to follow for the rest of your life.

While you may be feeling young, wild, and free, your decisions today directly impact your life down the road. No one's perfect and it's good to be open to change, but when it comes to your health, there are certain things you just can't argue with. Science proves that certain behaviors are linked to well-being and longevity, while others affect you negatively, causing suffering now and even later in life. All it takes to ensure you're giving yourself the best chance at a long, happy life, is breaking some bad health habits we're all inclined to give in to. Simple choices you make today will set you up for future success, tomorrow and beyond. Here are the habits you need to ditch, and how to break them.

1. Not getting enough sleep

One of the biggest bad health habits plaguing twenty somethings is not getting enough sleep. Eight hours of shut-eye is said to be the healthy ideal, but between late nights at high-pressure jobs and staying out super late on weekends to blow off steam, many in their 20s are not meeting this quota. It's proven that lack of sleep affects you throughout the day and undesirablethings happen to your body when you sleep poorly. Sleep deprivation affects your body's immune system, hormone levels, mood, and decreases your ability to focus. Still, sleep, let alone good sleep, is hard to come by. Unhealthy bedtime habits and bad habits keeping you up at night can be blamed for making things worse.

Break the habit:

You need to be proactive about making an effort to get more sleep. It is recommended to avoid caffeine for eight hours before bedtime and to remove distractions as you wind down for the evening. Watching your favorite show at the end of a workday might seem ideal, but you're apt to fall asleep with your laptop in your bed much later than planned and your quality of sleep will suffer for it. Have an evening routine that signals to your body that it's time to catch some Zs, like a hot shower and taking a few minutes to stretch. Block out excess light and sound from your bedroom as much as possible.

2. Forgoing sunscreen

It's well known that scary things happen when you don't wear sunscreen, yet it's one of the simplest health habits that we still get wrong all too regularly. From not using sunscreen correctly to not wearing it at all, twenty somethings put themselves at risk for a lot of sun damage that is actually avoidable. Sunscreen is important for more than just cosmetic reasons, but your future self will thank you later for protecting yourself from sun spots, broken blood vessels, and wrinkles.

Break the habit:

Train yourself to wear sunscreen daily, even when it's overcast. If you wear makeup, chances are your foundation has sunscreen built in. Otherwise, check out these non-greasy sunscreens you can wear under your makeup. If you lather up before sun exposure but still find yourself getting burned, you may be applying sunscreen wrong. Study up on these sunscreen mistakes everyone makes to improve your sunscreen game in the future.

3. Not drinking enough water

Chances are you're not drinking enough water. If you relate to any of thesesigns you're dehydrated or are experiencing any of these things happening to your skin, it's time to drink up. Staying hydrated has tons of immediate benefits to your wellbeing.

It helps to clean toxins from your body via your kidneys, keeps your muscles and joints working better, and helps keep you motivated and your memory sharp. The ways drinking enough water changes your body are hugely positive and definitely worth the extra effort to get in a few more glasses each day.

Most people would rather not buy homes in a known dangerous area, especially when the risks can't be removed.

Attom Data Solutions looked into how exposed over 3,000 US counties are to six natural hazards: earthquakes, floods, hurricane storm surges, tornadoes, hail, and wildfires.

They found that median home prices in the lowest-risk counties rose more rapidly than the highest-risk areas over the past 10 years, profiting homeowners. That's not shocking, since fewer people want to live near danger.

And over the past five years, sales volume fell below the national average in the most hazardous areas.

Attom also created an index for each of the six risks, and computed a total natural-hazard-risk index.

Using their data, we ranked the 18 counties with the highest index value in ascending order. We also included the one-year percent change in sales, one-year home-price appreciation, the hazard risk indexes that were deemed "very high," and whether home prices are above the US median.

Here are the riskiest counties:

Brunswick County, North Carolina

"Very high" hazard risks: Hurricane, flood, wildfire

One-year change in sales: -3%

One-year home-price appreciation: -1%

Price over US median? No

Source: Attom Data Solutions

Santa Clara County, California

"Very high" hazard risk: Earthquake

One-year change in sales: -7.7%

One-year home-price appreciation: 7.7%

Price over US median? Yes

Source: Attom Data Solutions

Miami-Dade County, Florida

"Very high" hazard risk: Flood

One-year change in sales: -9.7%

One-year home-price appreciation: 6.8%

Price over US median? Yes

Source: Attom Data Solutions

To get a job at Goldman Sachs, you've got to know your stuff. But financial knowledge alone isn't enough to land you a highly coveted gig at the financial giant.

To make the cut, you'll need to prove you have the skills, experience, and motivation to thrive — and you'll also need to prove that you're a good cultural fit. In other words: You'll need to ace the interview.

We sifted through reports from Glassdoor to find some of the trickiest and diciest interview questions Goldman has to offer.

Whether you're applying to be a summer associate or a VP, here are a few questions to master before you walk in the door.

This is an update of a story originally written by Rachel Sugar.

SEE ALSO: 13 tough interview questions you may have to answer if you want to become a flight attendant

'If you were an object, what would you be?' — Financial-analyst candidate

'How many square feet of pizza are eaten in the US each year?' — Programmer-analyst candidate

'What is more important, creativity or efficiency?' — Operations-analyst candidate

The EpiPen is the latest drug facing drug-pricing pressure.

But it wasn't always this way. 

The injectable delivers a dose of epinephrine, otherwise known as adrenaline, to treat extreme allergic reactions.

It's been around for more than a century. And the pen that delivers the medication has been around since the 1970s, when it was first developed for the military.

Since 2007, the price for a two-pack has gone up from $93.88 to $608.61, an increase of more than 500%.

Here's the story of how a device that's now a household name became one of the most controversial drugs of 2016.

SEE ALSO: The makers of the EpiPen just made a move to try and put an end to growing fury over the drug's price

DON'T MISS: The maker of EpiPen isn't out of the woods yet

Epinephrine, another name for the hormone adrenaline, is something our bodies produce naturally. It increases blood flow to the muscles during "fight-or-flight responses."

Source: Mental Floss

Japanese chemist Jokichi Takamine is credited as one of the first people to discover and isolate adrenaline as its own chemical. Not long after its discovery, scientists figured out how to produce it in large enough quantities to see how it could be used in different medical settings.

Source: The Practice of Medicinal Chemistry

Doctors continued to investigate how adrenaline works during the early part of the 20th century. In the past 100 years, it's been extensively studied, with more than 12,000 studies referencing it.

Source: Pharmacological Reviews, PubChem

For most of Volvo's 89-year history, the Swedish automaker offered its loyal legions of customers well-built, safe, and practical transportation with a certain Scandinavian flair. Now, the company's diving head-on into the world of luxury cars.

On the heels of the hugely successful introduction of the XC90 luxury SUV, Volvo introduced its new flagship luxury sedan — the S90. The new S90 replaced the company's S80 sedan. Although still a nice car, the current S80 has been on sale with minimal revision for nearly a decade. It is certainly showing its age. And the conservatively styled S80 hasn't been able to drum up the big sales figures Volvo would like to see from the model.

With the arrival of Volvo's new S90 luxury sedan, we take a look back at the company's flagship four-door sedans. Although they may not have always been overly luxurious, Volvo has always offered a big executive ride for those who sought the experience.

SEE ALSO: Former 'Top Gear' host Jeremy Clarkson just revealed the cars he hated the most this year

Although Volvo's foray into the car business started in the mid 1920s, its first offering with a luxury tilt was the PV 654 in 1933. It featured an upgraded, plush interior, twin spare tires and a reversing light. It was powered by an 80-84 horsepower 3.67-liter, 6-cylinder engine.

In 1935, Volvo followed up with the sleek PV36 "Carioca." In addition to the aerodynamic body, the Carioca featured advanced independent front suspension and room for six.

Volvo built a total of 501 Cariocas, powered by the same 3.6- liter, 6-cylinder found in the PV654. Volvo claimed a top speed of 75 mph.

They say everything's bigger in Texas, and we're here to show you it's true.

If the Lone Star State were its own country, it would have the 10th-highest gross domestic product in the world.

Some of that growth is attributed to Texas' energy businesses, though it has been hurt by the oil crash over the past two years.

Texas still dominates livestock production and is a leader in renewable energy.

Here are some stunning facts about this key state:

Texas has enough crude-oil reserves to fill up almost 1,862 Empire State Buildings.

Texas had 12.27 billion barrels of crude-oil reserves in 2014, or 515.42 billion gallons. That's 33.7% of US reserves.

The Empire State Building's volume is 37 million cubic feet, or 276,779,000 gallons.

Source: US Energy Information Administration

There are enough registered machine guns in Texas to arm every student enrolled at Harvard and Dartmouth.

There are 34,848 registered machine guns in Texas.

There are about 21,000 students enrolled at Harvard and about 6,300 students at Dartmouth.

Source: Bureau of Alcohol, Tobacco, Firearms and Explosives

Thirty-seven Wyomings would still have fewer businesses than Texas.

There were 2,356,748 firms in Texas in 2012.

There were 62,427 in Wyoming in 2012.

Source: US Census

Everyone's path to success is different.

For some, it's mostly linear. Others encounter more twists, turns, and bumps along the way.

While some like Steve Jobs and Richard Branson were already dominating the business world at 25, others like Larry Ellison and Mark Cuban took a little longer to hit their stride and saw their mid-20s as transformative years.

To illustrate how no two paths to success are alike, we've highlighted what 26 highly successful people were doing at age 25.

Vivian Giang and Max Nisen contributed to earlier versions of this post.

SEE ALSO: Tony Robbins, Richard Branson, and 28 other successful people share their best career advice for people in their 20s

DON'T MISS: 16 things successful 20-somethings do in their spare time

Donald Trump took over his father's real-estate-development company

Trump, a billionaire real-estate mogul, and animated TV personality, grew up wealthy. But as he told Forbes, his father wanted him to learn the value of money.

As a kid, his dad would take him to construction sites and have him and his brother pick up empty soda bottles to redeem for cash. He says that he didn't make much, but it taught him to work for his money.

At 25, the young real-estate developer was given control of his father's company, Elizabeth Trump & Son, which he later renamed the Trump Organization, according to Bio. He soon became involved in large, profitable building projects in Manhattan.

Jennifer Lawrence was an Oscar-winner raking in millions

At just 26 years old, Lawrence is Hollywood's highest-paid actress, raking $46 million pretax over 12 months this year, and closer to $52 million last year, according to Forbes.

By the time she was 25, Lawrence had starred in the box-office-hit "Hunger Games" trilogy and worked alongside a star-studded cast in the X-Men series.

At 22, she became the second-youngest winner of the Best Actress Oscar for her performance in "Silver Linings Playbook," and she has won many more awards for her work.

Steve Jobs took his company public and became a millionaire

By the end of its first day of trading in December 1980, Apple Computer had a market value of $1.2 billion, making its cofounders very rich men. Jobs, one of the three cofounders, was 25.

He later told biographer Walter Isaacson that he made a pledge at that time to never let money ruin his life.

The way most Americans build wealth is no secret: Save, invest, repeat. How average people keep their wealth, though, gets a lot less attention.

It boils down to how they handle risk. It's hard to accumulate wealth without taking some risks, but there are perils that "next-door millionaires" seem to avoid.

Next-door millionaires weren't born into wealth. They haven't invented killer apps or won the lottery, exercised a pile of stock options or played professional sports.

They're the majority of millionaires, and they include teachers, small business owners and professionals who accumulate wealth gradually over time. They're often in their 50s or 60s before their net worth ticks over to seven digits.

Research into how they think and act can give other regular folks some good insights. Here are some rules of thumb you might consider applying to your own finances.

SEE ALSO: I'm worth $1.5 million, and here's my best advice about getting rich

1. Follow the 'One house, one spouse' rule

Marriage can really benefit your financial life. People who get and stay married tend to be much wealthier than never-married singles, according to research by Jay Zagorsky at Ohio State University. By retirement age, married people have nearly 10 times the financial assets of singles, according to a study by the National Bureau of Economic Research.

But divorce can dramatically shrink your wealth. Zagorsky found that people who split up experience an average wealth drop of 77 percent. So while the uber-rich may be able to divorce and remarry with relative impunity, dividing assets can be wickedly costly for everyone else.

Sticking with one house can pay off, too. Every time you sell a house and buy another, you're giving up a chunk of your wealth to commissions and moving costs. Trading up also means staying in debt longer if you take on a new, 30-year mortgage with each purchase. If your home has appreciated substantially, you also may owe capital gains taxes on the sale. (The first $250,000 of home sale profit is exempt for singles, or $500,000 for a couple.)

If instead you keep the house and bequeath it to your heirs, it gets an updated value for tax purposes, and that gain is income-tax free. Paying off a single mortgage over time, or refinancing only to shorter-term loans, can leave you with a ton of equity that you can borrow against in an emergency or use to help finance your retirement.

2. Take risks, but don't gamble

"Safe" investments don't get you anywhere. The returns on Treasury bills and bank accounts insured by the Federal Deposit Insurance Corp. don't even keep up with inflation, so you're actually losing wealth over time. But next-door millionaires aren't speculators, either. Millionaire portfolios tend to be widely diversified, with investments in stock funds, bonds, cash and real estate.

The most popular investment choice? Low-cost Vanguard index funds, according to the 2014 CNBC Millionaire Survey.

3. Teach your children well

Some people question the value of a college education, but in wealthy families, it's usually a given, says Myra Salzer, an inheritance coach and founder of the Wealth Conservancy in Boulder, Colorado.

Nine out of 10 millionaires surveyed by BMO Private Bank in 2013 had a college degree and over half had a professional or graduate degree. (For comparison, just 36 percent of people ages 25 to 29 had college degrees in 2015 and only 9 percent had graduate degrees, according to the National Center for Education Statistics.)

Eight out of 10 millionaires told the 2014 CNBC Millionaire Survey that wealth inequality was due at least in part to wealthier families' greater access to education. Encouraging your kids to go to college, and helping to pay for it if possible, could help your kids get on the right side of the have versus have not divide.

When Will Dean proposed a teamwork-based challenge where participants have to trudge through mud and obstacles involving barbed wire, judges at the Harvard Business School competition were skeptical of his idea.

Who on earth would voluntarily put themselves through so much grueling pain, never mind pay to do it?

But a year later, the first Tough Mudder event took place at Bear Creek Mountain Resort, in Pennsylvania.

Seven years later, Tough Mudder has become a symbol of the ultimate endurance event, with over 2 million participants to date.

Unlike marathons, triathlons, or Ironman competitions, Tough Mudder is not a race. Participants are not timed, and there is no winner or loser. Instead, the emphasis is on teamwork and camaraderie.

Past challenges have taken place in North America, Australia, the UK, Ireland, and Germany, and the company plans to add China, Indonesia, and the United Arab Emirates to the list.

Business Insider recently visited Tough Mudder's New York headquarters for a glimpse of what it's like to work for a company that strives to push people past their mental and physical limits.

SEE ALSO: The company that wants to build 'Disney for dogs' is starting with an office full of toys, treats, and canine coworkers

DON'T MISS: Step inside Spotify's New York City office, where you'll find an airy roof deck, cold brew coffee, and a secret recording studio

DON'T FORGET: Take a tour of the New York City subscription startup where you'll find swings, sneakers, and gnomes

Tough Mudder's New York headquarters is located in the newly developed MetroTech Center in Brooklyn. It is home to about 120 employees.

The reception area is filled with Tough Mudder memorabilia, and a TV displays footage of challenge participants all over the world.

Tough Mudder-branded swag is present everywhere in the office. The monkey below sports its signature orange headband, which is given to all Tough Mudder participants when they enter the challenge.

Dwayne "The Rock" Johnson was just named the highest-paid actor in the world. According to Forbes, the former WWE star makes $64.5 million per year, beating out the likes of Robert Downey Jr. and Brad Pitt.

One of the hardest working people in show business, Johnson stars in movies and TV shows, runs his own production company, and gets a few extra bucks from endorsements. Yet, the actor also knows how to enjoy himself and spend his hard-earned cash.

Here's how The Rock spends his millions.

Forbes named Johnson the world's highest-paid actor for 2016 with a whopping $64.5 million a year. The former wrestler works hard for his millions.

Source: Forbes

Johnson is a box-office juggernaut. Past successes have led to him commanding bigger pay days for upcoming films.

A few recent hits include:

"Furious 7" (2015):$1.5 billion
"San Andreas" (2015):$474 million
"Fast & Furious 6" (2013): $788.7 million

Source: Forbes

His most recent film, "Central Intelligence," grossed $210.3 million worldwide.

Source: Box Office Mojo

London is full of street food markets offering an array of delicious food from all over the world.

With so many options, choosing just one stall for lunch can be daunting.

To find out what we should be eating, we teamed up with Expedia and compiled a list of the one dish to try at street food markets across the capital.

From a gourmet goat wrap to halloumi fries, here are 13 scrumptious street eats every Londoner should try:

Get a "Submarine" sandwich at Lower Marsh Market.

The "Submarine"— a sub sandwich heaped with seared scallops, roasted pulled pork shoulder, blackened calamari, a dollop of lemon and parsely mayonnaise, pork crackling, and rocket — is the favourite roll offered by sandwich makers Sub Cult.

Where to get it:Lower Marsh Market

Try not to make a mess as you eat this mammoth burger at Malty Street Market.

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African Volcano's "DirtyLittleSecret" burger is made with char-grilled beef, 18-hour slow-roasted pulled pork, Emmenthal cheese, lettuce, tomato, peri peri mayonnaise and sauce, a gherkin slice, and sautéed onion. Though it's messy — the bun barely contains the filling inside — the burger is a favourite with customers.

Where to get it:Maltby Street Market

Try spicy, cheese-covered fries at Portobello Market.

If you're a fan of chips, try the "Lucifer Fries" from expert chip-maker Poptata. The hand-cut fries come served in a traditional paper cone, heaped with grated cheddar and Red Leicester cheese and flavoured with spicy paprika sauce, garlic, rosemary, and thyme.

Where to get it:Portobello Market

The pitter-patter of tiny feet is one of my favorite sounds to come home to at the end of a long day. 

And I'm convinced that my dog, Izzie, is just as elated to see me as I am to see her.

But what's she really thinking when I open the front door and our eyes meet? Is she simply excited for the dinner I'm about to feed her, or do we have a real bond?

To find out more, we spoke to canine behavioral researcher Julie Hecht and Duke University professor of cognitive neuroscienceBrian Hare, who wrote the book "The Genius of Dogs," and hosts a new podcast called DogSmarts.

Here are a few of the recent discoveries that Hecht, Hare, and other scientists have made about dogs:

DON'T MISS: I got my dog’s DNA tested and what I learned shocked me

SEE ALSO: How to know if your dog hates hugs

1. Why does my dog get so excited whenever I say the word 'walk'?

Dogs, like dolphins, apes, and parrots, can learn a series of vocal commands or words. One dog, a border collie named Chaser, learned more than 1,000!

Researchers say Chaser used a process called “fast-mapping,” or inference, which is pretty similar to how human children learn language skills. Basically, it involves guessing the meaning of a word based on the object that is being used in conjunction with that word. So if you're constantly saying "walk" and then fetching your dog's leash and taking him outside, he may be able to infer that the word "walk" has something to do with the action of going for a walk.

2. Why does my dog yawn every time I do?

Just like people, dogs can "catch" yawns. A study in the journal Biology Letters says this "emotional contagion" is completely normal. More importantly, the researchers write, your dog catching your yawn is a sign of basic empathy.

Dogs are believed to empathize with us in other ways as well. A University of Helsinki study suggested that dogs can sense when their owners are angry and have even evolved to respond accordingly. Another study found that dogs respond in a similar way, physiologically and behaviorally, to people when they hear a human baby crying.

3. Why do dogs turn away from us when we try to hug them?

A psychologist who studies canine behavior found a disturbing trend in 250 photos of people hugging dogs— the dogs were not happy. How do we know? According to animal behavior researcher Julie Hecht, there are three common signs of stress in dogs: 1) Turning their heads away from the thing that's bothering them; 2) Showing the whites of their eyes; and 3) Lowering or pinning back their ears. Most of the dogs in these photos were showing these signs.

Still, some dogs might tolerate a hug, especially if it comes from someone familiar. In other words, dogs have myriad ways of showing affection, but hugs may not be one of them. "Interactions work best when dogs set the tone and pace," Hecht told Business Insider. "Let friendly dogs initiate contact through sniffing and then show you where they want to be pet."