Heel Touches

Setup
Lie on your back with knees bent and feet shoulder width apart, with arms by your side. Roll shoulders up off the ground by flexing at the waist.
Movement Instructions
Bend to the side at your waist and reach down with one arm to touch your heel, then bend the other way and reach down to touch the opposite heel. Repeat.
Comments
Hips and legs should not move at all, bending should happen at the waist and upper torso and shoulders should move back and forth.