Rick Gore tells us how to stop a horse from walking off when you mount. The reason why a horse walks off when you mount it, it's because you trained it that way, when you've mounted previously you would allow it to mount off. Also when you mount you cause the horse to lose it's balance, and when a horse loses it's balance, it starts to walk a bit to regain it's balance. To stop a horse to from losing it's balance you should square it up, push the horse a little bit and it's feet will square up allowing him to balance more. When getting onto your horse you want to lunge pretty big as soon as you're about to sit on the horse make sure to go right over the horse.