Keep working your arms with a set of push-ups. Make sure to tuck your tailbone, keeping your hips and thighs in a straight line with your feet in line with your hips. Hoebel suggests rolling up a towel lengthwise and placing it underneath you so that it runs from your waist to your chin. Make sure that your chest and waist touch the towel at the same time to ensure proper form, which will work your abs, hip flexors and thighs in addition to your arms.
Advanced version: Work your hamstring and lower back by doing this exercise with one foot raised off of the ground.
Brett's Tip: Squeeze your legs, butt and abs when you exhale and push off of the ground.