Having a Ball: Sex on an Exercise Ball. Get a large exercise ball (or firm large beach ball). The woman lies back on it, with her legs spread, feet flat on the ground, head pointed up or resting back on the ball, and fingers reaching toward the floor for support. The guy kneels or crouches slightly between her legs, then enters her. He can continue kneeling while holding her hips as he thrusts, or he can stretch his body over hers and use his feet on the ground for support. She can grab his butt and draw him into her, or keep her hands on the floor for balance as he moves in and out.  If you enjoy deep penetration, this position will certainly give it to you. Maintaining your balance on the ball forces the woman to tilt her pelvis upward slightly, so the man experiences deep penetration. The exercise ball will stay in place firmly under the woman,  unless he thrusts very hard or fast. He’ll need to restrain his motions — no wild bucking — which will keep his desire on a slow, superhot boil.