A challenging program created to reshape the back of your body: back, biceps, buttocks and hamstrings. Jillian Michaels, the boot-camp-style trainer from TV's The Biggest Loser, is tough, demanding and relentless (do not stop, I know you can do this!).

Like all her workouts, the format is straightforward - a fast-paced series of individual exercises (10-30 reps per set, each set never more than one-minute long). For example, morning glories, jump lunges, plank twists, double crunches, side lunges.