Double Leg Glute Raises
Sit on the ground with your upper back resting on a chair or couch with your feet on the floor and your knees bent. Plant your feet firmly and thrust your hips up, pushing your belly button to the ceiling.
Squeeze your glutes to create a bridge where your back to your knees is flat.
Hold for 3-5 seconds, and then return to the starting position.
Do this 10-15 times, really generating a thrusting motion with your hips and glutes.