How do I perform side power step-ups?

Stand beside a box with your feet pointed straight ahead and placed shoulder-width apart. Lift your chest and tuck in your chin. Contract your glutes and place one foot on top of the box. Forcefully push off the foot into the air driving your body sideways across the box. Land softly on the opposite side of the box with your opposite foot on the box. Repeat the action quickly, alternating sides and feet as your move across the box.