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

Use a box or aerobic step approximately 6" tall.  Begin standing on the side of the box with a slight bend in your knees and your weight on the balls of your feet.  One foot will be on the box and the opposite foot will be on the floor.  Moving both feet at the same time, hop across the box so your switch positions.  The foot that was on the box is now on the floor and the foot that was on the floor is now on the box.  Repeat this hopping pattern for the designated time, moving as quickly as possible while maintaining control.