Living the celebrity lifestyle means doing nothing halfway, so is it any surprise that so many stars go all out in their athletic pursuits? Sure, there are plenty of weekend golfers, and stars who only hop on the treadmill to stay in shape for that next big role, but there is also a slew of top talents who run marathons, compete in triathlons and play hockey and basketball like the pros. Here's a peek at a few of Hollywood's top jocks.