Lie on your back with your knees bent and your feet flat on the floor.
Flatten the curve of your back against the floor, tighten your buttock muscles and lift up your hips.
Hold this position, keeping your hips level.
Lift one heel up off the floor keeping your toes in contact with the ground.
Lower your heel back down.
Lift the heel of the other leg.
Alternate both legs, keeping your hips levels throughout.
Bring your hips back down and relax.