HOW: Start in the quadruped position on your hands and knees. Push the ground away from your and engage your serratus anterior. Keeping that engagement, slowly push the ground away from you forward with your hands, which will cause your body to go backwards.
FEEL: You should feel all the muscles in your shoulder working, especially under your shoulder blades.
COMPENSATION: Do not simply rock back by using your legs or just sitting back. Use your shoulders to drive the movement.