Single Leg Hip Thrusters

Lay back on a bench with your upper back resting on the bench and the rest of your body hanging off in line with your torso. Your feet are both flat on the floor, with your knees at a 90 degree angle.
Lifting one leg off the ground and extending it straight, squeeze your glutes and lower your hips halfway to the floor then raise your hips back up until they are in line with your torso again.
Repeat for number of reps and then repeat for the same number of reps on the opposite side.