If your horse has a tendency to race ahead when you’re riding in a group, here’s a way to teach him to relax. Find a controlled environment like an arena or a large pasture and enlist the help of a friend on horseback. Start at the walk and ride side by side, about 15 feet apart. Keep both horses on a loose rein and dare them to race ahead. If at any time either horse speeds up, immediately pick up on one rein and turn the horses toward one another and head back the other way. When you turn your horse, do so with urgency so that he has to hustle his feet. If you just let him turn lazily, he’s not going to connect racing ahead with stopping his forward motion and having to redirect his energy.
When you’re headed in the new direction, be sure to put the horse back on a loose rein and dare him to make a mistake again. In order for the horse to learn, he has to commit to the mistake. If you try to babysit him and keep him from speeding up, he’ll never get any better and you’ll always have to watch over him. Practice the same steps at the trot and then the canter. It shouldn’t matter what gait the horse is in, he should remain at the speed you set him at and not race ahead.
With repetition, the horse will realize that when another horse comes up beside him, it’s not a race, and he better keep his attention on you because at any second you might change directions and go back the other way. If he does speed up, he’ll quickly realize that it doesn’t matter because you’ll make him turn and go the other way. The hotter and more nervous your horse is, the shorter the distance will be between turns initially. Eventually, he’ll be able to walk next to the other horse on a loose rein without ever speeding up.
Courtesy of Downunder Horsemanship