Butt-Ups

Begin a pushup position but with your elbows on the ground and resting on your forearms. Your elbows should be bent at a 90 degree angle. Arch your back slightly out rather than keeping your back completely straight. Raise your glutes toward the ceiling, squeezing your abs tightly to close the distance between your ribcage and hips so you end up in a high bridge position. Lower back down slowly to your starting position. Repeat. Don't let your back sag downwards.