Stand tall with your right foot atop an aerobic step, the left foot on the ground and your body parallel with the step. Push through your elevated foot, moving it laterally to the ground on the other side of the step. Simultaneously bring your left foot onto the top of the aerobic step. Keep your landings soft by bending your knees as your feet touch down. Continue alternating legs and repeating the movement for the required number of reps (or time).