Hold a medicine ball in your left hand at chest level as you lie on the floor, knees bent.

Simultaneously lift your shoulders off the floor, lift your left leg up, extend your left hand and pass the ball under your left leg to your right hand. Once it's in your right hand, lower your torso and left leg. Next, lift your right leg as you raise your upper body and pass the ball under your right leg to your left hand. Alternate sides. Keep both feet off the floor for the set.