Tony Hawk knows that when you're hurtling down a halfpipe into an aerial spin, losing focus could get you seriously hurt. After co-founding a skateboard company in 1991, Hawk learned that distractions in the business world can be equally dangerous.

When we first started, I was doing all the marketing and all the promotional materials myself. I was OK at it, but I wasn't the most qualified person. Finally, one of our team members said, "Your ads aren't very good. You're better at skating. Why don't you let me take this over?"

So I took a step back from the business and focused on skating. I stopped being so involved in the day-to-day operations and became more of an adviser. The company was growing, and everything was working out pretty well. But all that changed when we started to move outside of the skate world.

A friend of mine persuaded us to sell his high-end denim line. It sounded like an awesome idea, but we had no idea about the clothing industry. It sucked up our profits for a good two years. After wasting a couple million dollars, we ended up selling the line to another company just to get out of debt.

Not long after that debacle, my partner, Per Welinder, told me he wanted to acquire a surfboard brand, too. After what we'd just been through, I didn't want to do it. I didn't know enough about surfing. Besides, this wasn't why I got into business. I got into it for skateboarding.

Per and I weren't seeing eye to eye, so I offered to buy him out. It took him about a year and a half, but he finally said yes. It was a relief, because I could finally do what was best for skaters again. I started licensing the brand and launched a new line of skateboards that were sold at a mass level in stores like Target and Walmart.

These days, it's easier for me to turn down opportunities that don't fit the brand. I have the confidence to say no.

Age when he turned pro: 14
Start-up capital: $80,000 of the co-founders' personal savings
Total video-game sales: More than $1 billion through a licensing agreement with Activision