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 as you simultaneously lift your hips up to come into a bridge position. Make sure to keep your spine in a neutral position, meaning there shouldn't be an excessive arch or rounding of the spine.
Press your right heel into the floor, and keeping your knee bent, raise your left foot off the ground until your hip is at a 90-degree angle.
Maintaining the bridge position, lower your left leg down to the ground.
This counts as one rep. Continue to alternate marching between the right and left sides.