Sit on a bench with your hands either side of your hips, gripping the edge of the bench firmly. Place an aerobic step parallel to the bench in front of you. Lift up onto your hands, bring your hips forward and extend your legs out in front of you until they are straight with your feet resting on top of the aerobic step. Keep your elbows tucked in close your body as you bend them and lower your hips down. Keep your core braced throughout, your shoulders down and your hips close to the bench. Inhale as you lower. Pause and then push back up until your arms are fully extended again, but be sure not to lock your elbows. Exhale as you do so. Repeat for the required number of reps (or time).