Lie on your back with your hands by your side, with 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 a 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.