When you slouch, you tilt your pelvis forward, pooching out the tummy and giving the appearance of a thicker midsection. These isometric exercises will help you learn how to strengthen your abdominal and gluteal muscles, says Cedric X. Bryant, Ph.D., chief science officer for the American Council on Exercise. "They act like guide wires to keep you from pressing your pelvis forward and arching your back," he adds.
Glute Squeeze: Firmly contract your glutes and thighs while standing upright and still. Hold for 10 seconds (remember to breathe!), then relax. Repeat 10 times.
Ab Brace: While standing motionless, tighten your abdominal muscles as if you were anticipating a punch to the stomach. Hold for 10 seconds, then relax. Do ten of these. They'll smoothe out the appearance of a potbelly while toning and strengthening the abs, Bryant says.