I love the ball. My favorite move is a one-legged plank. Hands on floor. One foot on ball. One foot in the air. To make it really hard, take that "floating" foot, lift it up behind you and around to the other side, touching the floor. For example, if your left foot is on the ball and your right foot is in the air, then your right foot would come around and touch to the left side on the floor." - Alexandra Williams of
Fun and Fit