To perform this exercise, lie face up with knees bent, feet flat on the floor, and arms resting on each side of your body. Keep your knees close together, squeezing the muscles on your inner thighs. Squeeze your glutes and hamstrings to lift your hips off the floor, keeping your core engaged throughout, so that your body forms a straight line from the knees to the shoulders. Lower hips and repeat. You can do two sets with 15 reps each set. If this is easy, try the same exercise with a resistance band placed around your thighs.