What it does: Works the sides of the abs and the shoulders.
 
 How to do it: Kneel with your left side leaning against the ball. Straighten your right leg to the side, foot on the floor. Raise your left arm overhead and point your right arm straight out to the side. Bend to the right a few inches, right arm pointing toward the floor, then raise your torso slowly. End with your right arm up and your left pointing to the left.