Ron Farmer is a speed freak. When his knees failed at 52 years old, he quit running marathons and began racing cars. Ten years later, he is headed to Ohio to drive his Corvette in the National Auto Sport Association's National Championships.

"I always wanted to race a car for the thrill," he says, "I had that need for speed."

But Farmer started slow, participating in autocross events--timed competitions where drivers navigate a course of traffic cones--in the same Mercedes he drove to work.

He found autocross competitions a way to bond with his son BJ, who also liked the sport. But it wasn't long before BJ moved to the high speed track and after five years of autocross without his son, Farmer decided to shift gears.

"I realized I was doing it because I wanted to do it with him," he says. "We need things to keep us together." Farmer learned enough on the autocross track to complete a high-speed certification course in a weekend and was off to the races.

The fear involved in wheel-to-wheel competition engrossed Farmer. The element of danger in turning corners at high speeds with other cars drove him headlong into the sport.

"I drive differently when I see someone in front of me," he says. "It's about the competition. I want to win." Farmer's attitude toward racing shows itself in his entrepreneurial approach at US LED, ranked No. 910 on this year's Inc. 5000 list, where he claims he would work for free if it meant thwarting his corporate competitor GE.

For now, however, he will focus his competitive spirit on the NASA Championships in September, where he hopes to celebrate his 62nd birthday with a victory.

Kirsten Bradford, Spohn Ranch

At first glance it's hard to believe Kirsten Bradford spends her free time powering a 220-pound dirt bike up precipitous desert terrain. But the CEO of one of the world's leading fabricators of skate parks says that despite her diminutive stature she is hooked on motocross.

"There's a real sense of accomplishment; for someone my size the bike is heavy and after an hour it's tiring," she says. "But it's the most exhilarating feeling I've ever had--I'd recommend it to anyone."

Bradford drove a street bike during her days at UCLA, but refused to join her brother Mark on his motocross trips until 1999, when she promised to tag-along if he shaved off his goatee. Within hours he was clean shaven and told her to pack her bags.

This wasn't the first time Kirsten partook in her brother's antics; she wouldn't be where she is today if she hadn't decided to tag along.

In 1990 Mark befriended Aaron Spohn, a 30-year-old construction worker down the street who -- to the dismay of his landlord and neighbors -- built an enormous half pipe in his backyard. "Spohn Ranch" soon became a hangout, not only for Kirsten and the neighborhood knuckle-draggers but for some of the most talented in-line skaters and skateboarders around.

"People would just show up with their bags on their backs," Kirsten recalls. "Japanese kids would be at the door and say 'Hey can we stay here?' There was no plan; it was all word of mouth."

When ESPN called Aaron in 1993 and asked if he could help build the ramps for an extreme sports competition called the "X Games" Spohn Ranch became more than a neighborhood hangout for Kirsten and her brother. Aaron, who held down his full-time job, needed the two to help him buy materials, take care of financials, and work with ESPN to plan the logistics of their event.

Kirsten was eventually so busy she dropped out of UCLA. Luckily, she never needed the degree. The first X Games went well and Spohn Ranch, Inc. was flooded with phone calls from municipalities worldwide looking to build their own hometown skate park. The company is now ranked at No. 4798 on this year's Inc. 5000 list.

Gary Davis, Davis Trucking

Most CEOs don't unwind on the weekend by strapping themselves to the front of a 522- cubic-inch boat motor and dropping the pedal to the metal, but for Gary Davis there is nothing more relaxing.

The regional trucking company owner travels the country with three of his best friends to compete in the International Hot Boat Association's yearly drag boat racing series.

Drag boat racing, much like drag racing, is a quarter mile straightaway acceleration race between two high performance boats.

Davis bought his first flat-bottomed drag boat at 26 after watching his father race as a kid. His father warned him of the addicting quality of the competition.

"He always told me you either get out of it or it kills you," Davis says, admitting his father was right, "Every year we just started going a little bit faster."

That was until one day in 1998 when Davis nearly took his boat airborne at speeds in excess of 150mph at a race in Bakersfield, California.

"The boat tilted into the air and landed back on its bottom," he recalls. "I road down the rest of the track, put it on the trailer and never drove it again."

Three months later however, he bought a safer "hydroplane" drag boat with a hull shaped like the pontoons of a catamaran. He christened it Cent$less (meaning "dumb and broke") and returned to the water.

Now Davis is holding fourth place in the 2008 IHBA Championship and he is confident he can still finish off the season on top.

"We're trying to get the high points championship" he says. "With three races left it's still mathematically possible. I think we still have a good shot at it."

Well, ranking at No. 2174 on this year's Inc. 5000 is almost as sweet, don't you think?

John Younger, Accolo

Ask former Olympic athlete John Younger if he is still rowing and he will show you the blisters on his hands.

"I haven't stopped for more than a month, maybe six weeks, since 1981," he says. "It's how I stay sane."

Younger, the owner and CEO of a recruitment outsourcing company, Accolo, No. 1036 on this year's Inc. 5000 list, first rowed as a freshman at Notre Dame and by his senior year he was determined to take his rowing career to the next level--from Notre Dame's club team to the U.S. Olympic squad. The leap proved harder than anticipated.

When Younger contacted the Princeton coach running the qualifying tryouts, he was told he had no chance against his Ivy League competitors.

"I asked him if I could just show up and he said 'absolutely do not just show up,'" he admits.

To the consternation of the coach, Younger arrived at the tryouts anyway and despite his underdeveloped technique, rowed faster than anyone there.

He was the last man cut from the 1984 Olympic team, but made the National squad the following year and won a silver medal at the World Rowing Championships in Belgium.

He never made it to the actual Olympic Games, but Younger balanced a budding career in HR development while competing on the international level, eventually breaking the world record for distance rowed in 1992 by logging more than 287,000 meters on a rowing machine in a single sitting.

Today, Younger rows enough on his own and for the Marin County Rowing Association. His wife calls his scull his "other woman." Without it she knows he'd have a hard time relieving the stress of running his company.

"When I row my thoughts are transitory," he says. "I don't hang on to anything except the rhythm and flow of the water underneath the hull."

Vinu Malik,

"The Ironman World Championship in Hawaii is the holy grail of triathlon racing," says Vinu Malik. On October 11, 2008, he along with 1,700-plus athletes from around the world will descend upon coastal Kailua-Kona to compete in the defining event of triathlon racing.

This will be Malik's 26th Ironman--a race consisting of 2.4-mile swim, a 112-mile bike, and 26.2-mile run--and his sixth performance at Kona. In past years he performed despite a bout with the flu, a broken nose, and severe dehydration.

Qualifying for the championships places Kona's competitors ahead of thousands of athletes worldwide who failed to earn a coveted spot in the race, but for Malik, reaching Hawaii required more than a rigorous training regimen.

As a college student Malik was bed-ridden by chronic fatigue syndrome. Though he lacked the energy to live a normal life, he saw triathletes on television and in magazines and they inspired him to begin spending his free time exercising.

"You'd think exercise would make you more tired," he says. "But it helped stimulate my system, and taught me to focus on my nutrition." Before long, Malik was training for an Ironman. But at 19 and still chronically fatigued he failed his first attempt.

"I had a lot of dehydration issues," he recalls. "So I came up with the Fuel Belt."

Malik designed a belt for holding water bottles to stay hydrated while running and biking. The invention was so successful he patented the idea and began selling Fuel Belts full-time. The company made No. 2384 on the Inc. 5000 list this year.

Now the nifty invention is essential equipment for endurance athletes everywhere. Last year, Kona's first and second place contestants sported Fuel Belts and this year over 700 contestants are expected to use one too.

"There is nothing cooler than watching people getting their picture taken at the finish line wearing their Fuel Belts," he says.