Lie on your right side on a mat, propping your head up using your right hand. Bend both legs at 90 degrees and ensure your heels are in line with the base of your spine. This is your start position. Focusing the tension on your left glute, drive your left knee away from your right, being sure not to let your hips rock back when doing so. This ensures the tension remains in your glute not your hip flexor. Exhale as you do this. Squeeze your glute at the top and then lower with the control to the start position, inhaling as you do so. Repeat all the required reps (or time) on one leg before changing to the other.