Why planks? Each move shifts your center of gravity and forces your abdominals, arms, back, and glutes to stabilize your body. Denver-based trainer Stacey Lei Krauss, the creator of a plank-infused cardio fitness program called the Willpower Method, designed this sequence, which includes several variations on the standard plank position. To get started, simply clear a space on the floor. Complete the entire cycle three times a week, taking 30 seconds between each move to roll your wrists and shoulders, and you'll achieve stronger muscles and a toned look without even touching a set of weights or (if you’re like Krauss, who prefers to go barefoot) donning a pair of sneakers.
To watch an example of one variation of the exercise, see How to Do a Plank.