Start lying face up on the ground with arms to the side, knees bent, and heels on the ground with your toes up. Squeeze your glute and abdominal muscles then lift your hips off the ground until knees, hips, and shoulders are in a straight line. Hold 2-3 seconds and return to starting position, repeat for the prescribed number of repetitions. You should feel this working mainly your glutes and secondarily your hamstrings. You should not feel any pain in your lower back. Tip: Be careful to not let your back hyper-extend.