Flat Belly Fast—No Crunches! Four moves that guarantee you'll get abs in six weeks Squat, holding a medicine ball next to your right hip (a). Keep your arms straight and raise the ball up and across your body until you're standing and the ball is above your left shoulder (b). Lower back to start. That's one rep. Do two sets of each move (eight to 10 reps per side) three days a week to streamline your silhouette fast.