1. Roll out onto ball in a prone position. The ball should be under your shins.
2. Keeping your hips and body parallel to the floor (no sagging of the hips) bring your legs in towards your chest.
3. Remember to keep your trunk parallel with the floor.
4. Now rotate towards your left and repeat back and forth until the desired number of repetitions is met. The ball should pretty much stay in one place. Keep your body in a somewhat straight line and somewhat parallel with the floor.
