DON'T: Slump. Your body's muscle memory will lock in the hunch and default back to it later unless you learn proper form.
DO: Put both feet on the ground and sit toward the edge of the seat at every commercial break. Squeeze your knees together and keep your head balanced over your tailbone. Work up to maintaining this posture for 60 minutes.
THE PAYOFF: Strengthens your core, helping you keep your hips and ribs aligned with your ears, shoulders knees and ankles