Jim Sullivan, 55, is part of the wave of older athletes dominating the field of ultra-marathoners.

What drives an extreme athlete? Find out from Ellyn Brown, a 54-year-old Alaskan who is the U.S. mountain running champ and one of the best snow shoe racers alive.

It's the ultimate motorized highwire act, requiring lightning-fast reflexes, incredible strength and stamina, and nerves of steel. For decades, motocross has been a young man's extreme sport. It's still extreme, but suddenly there's gray hair everywhere.

A housewife just wanted to lose 20 pounds. She ended up completing a 400-mile wilderness trek. Hear how she did it.

This over-50 extreme sports athlete makes peoples' jaws drop with only one wheel. Terry Peterson, best known as the UniGeezer, has become a worldwide sensation on a unicycle.

For a man who has run over 100 marathons at least 100 miles long each and climbed to the top of all the seven summits of the world, it's hard to believe Marshall Ulrich was a bit of a coach potatoes until he was almost 30.

How do you mark your birthdays? Even in his mid-70s, Norman Gitterman really likes to get off the ground for his.

Ray Zahab used to be a smoker who lived an unhealthy life. After a few major life changes, he's on the other side of the spectrum, running marathons, raising awareness for important causes and living an adventurous life.

Pat and Cat Patterson aren't your ordinary couple. Emerging from divorces and financial stress, the two met and decided to rebuild their lives together and did so as they bike across four continents and 57 countries in four years!

Time flies and so does this mother-son skydiving team. Growing Bolder found a unique tandem whose definition of spending quality time together involves taking the plunge at 13,500 feet.

This is a tense tale of determination; a celebration of passion and the human spirit. 93-year-old Banana George Blair, weak from a long battle with pneumonia and in constant pain from six back surgeries, wants to get his bare feet back on the water.