"Move. Your. Body," says Jen O'Brien, a 31-year-old bike messenger in Boston, one city notorious for its frigid temperatures and crazy drivers. "You need to put up with things like frozen wet feet for nine hours at a time and windburn on your face—but it's fun." In college, her roommate was a messenger, but Jen was overweight and didn't think she could ever do the job. "I couldn’t run two blocks to save my life," she says.
Eventually, though, Jen started commuting to work on a bike. The trip only took 20 minutes one way, but she started looking—and feeling—healthier. "I really didn't need to kill myself. I just need to do something repeatedly...only after becoming an active person did I know how great it feels to be in decent shape." So don't worry about following a super-structured exercise regimen or a gimmicky tape you ordered from an infomercial during a late-night moment of weakness. Just shake that cement out of your bones.