----------------------

Use a box or aerobic step approximately 6" tall.  Begin facing the box with a slight bend in your knees and your weight on the balls of your feet.  Step on the box with your lead leg and follow with the other leg then step down with your lead leg and follow with the other leg.  Continue this stepping pattern for the designated period of time leading with the same foot for the entire time.  Lead with the opposite foot on the next repetition.  Perform this movement pattern as quickly as possible while maintaining control.