The right leg is a brace that pushes hard into the ground as your hips slide forward. Did GM show you the drill where you push a golf cart with only your left hip in contact with the cart?
No he actually got in behind me grabbed my right knee with his left hand and pushed hard at my right hip with his right hand (going forward) as I was about 1/3 of the way back. Felt weird but effortless, never hit it better. Can you give me more detail regarding the cart drill please?