Lie on your back with your hands by your side and your heels about 12 inches from your pelvis. Press your heels into the floor to come into a bridge position with a neutral spine.
Press your right heel into the floor, and keeping your knee bent, raise your left leg until your hip is at 90 degrees. Lower your left leg down, pressing through your glutes so your pelvis doesn't drift to the floor along with the leg. This counts as one rep.