Photo credits: Top, James Michelfelder.
1. Place your hands on the floor at shoulder width, keeping your abs braced and your body in a straight line. Squeeze your shoulder blades together.
2. Keeping your elbows close to your torso, lower your body until your chest touches the floor. Engage your abs and lift your hands off the floor. Place your hands back on the floor and engage your chest and triceps to return to the starting position. That's one rep.