4 Fresh Twists on Old Workout Routines

The workout: This surfing-inspired gym class uses a body-weight-activated surfboard contraption made to mimic the real thing; you can adjust the board's level of instability to the degree of difficulty you want. Targeting the same muscle groups surfers use, the workout can include a taxing series of lunges, squats, and push-ups. (Surfset classes are offered in nearly 50 locations across the country, or you can order your own board, plus access online workout videos, at surfsetfitness.com.)

Why you'll like it: Sure, it's a bit gimmicky—but it's also genuinely exciting and has serious payoff. You'll craft a long, lean body, burning 400 to 900 calories in just one session. And thanks to the routine's Zumba-like fun, your workout will seem less like, well, work.