Stand with your feet shoulder-width apart and hands on hips. Now step forwards with your left leg, bending your right knee and dropping into the lunge position until your left thigh is parallel with the floor and right knee is almost touching the floor. Now push back up and jump up into the air. While you’re in mid-air, swap legs so that you land in the opposite lunge position with your right leg forwards and your left leg bent at the knee. That completes one rep.