When lungeing a horse, keep your core (belly button) directed toward the horse’s shoulder or girth area and the lunge whip directed toward the flank area, which is the “go” button on the horse.  Your core at the shoulder sends a pushing message asking the horse to stay out on the circle and the whip at the flank sends a pushing message to the horse to move forward.  Do not allow your core to drift in front of the horse’s shoulder toward his head.  This will cause stress in the horse and his body will become tense and “bent out of shape”.