Lying on your side, lengthen your bottom leg and cross your top leg over it. Rest either your knee or foot on the floor. Prop your head up with your hand, or rest your head on your arm.
As you exhale, lift your bottom leg up, and inhale as you lower it back down. As you exhale, lift your bottom leg, and inhale as you lower it back down without letting it touch the floor. Your torso should stay still while you do this. This counts as one rep.