Legendary skateboarder Tony Hawk has broken his pelvis and elbow, fractured his skull and had more than 20 concussions — but still won't walk away from the sport.

In fact, the 51-year-old sports star says that building a career out of skateboarding has been his most courageous move.

"I think that the bravest thing that I've ever done is to chase a skateboard career into my adult life. I have no breakup plan, so I hope it keeps working," he told CNBC's "The Brave Ones."

Hawk's older brother Steve got him into the sport in the 1970s, handing him an old skateboard at age nine and taking him to skate parks. "I literally saw people flying. Like, I saw these guys flying out of empty swimming pools. And that was my 'wow' moment. Where I was like, I want to do whatever they're doing," Hawk said.

Within five years at age 14, Hawk turned pro, and by 16 he was regarded by many as the best skateboarder in the world. According to his website, by the age of 25 he'd won 73 contests and was attracting a range of sponsorship deals. It's not the kind of activity that translates easily into a career — but Hawk made it so.