HOW: Start by holding a long towel while standing fairly close to a wall to the side of you. Begin by stepping towards the wall with the leg closest to the wall. Load that leg up by slightly bending the knee, hinging forward at the waist, and bringing the towel down towards that leg. As you step towards the wall begin to whip the towel into the wall with your momentum going towards the wall.
FEEL: You should feel your leg and core muscles working the most.
COMPENSATION: Make sure to keep your hips perpendicular to the wall even while whipping the towel.