Lay on your back with your feet planted on the floor, knees bent. Keeping your core tight and back straight, sit up to a 45 degree angle; coming up too high or too low will disengage your muscles before adding the punch. Throw out a Jab and Cross combination at the top of your Sit Up, remembering to keep your feet grounded. Return to the floor, keeping your guard up. On your next rep, Cross, then Jab. Alternate between these combos to build strength evenly. Protect your neck by activating your core and focusing on form, not speed. Challenge yourself!