Variety is the spice of life, the old saying goes. So after a long season during which pro athletes focus exclusively on the game they play, who can blame them for branching out and trying something new? And although some of their choices may seem logical (playing tennis to work on one's golf swing, for example), many are surprising—and at least one is downright dangerous. Curious to learn how some of your favorite athletes stay in shape off the field? View the slideshow.