When you’re working with an arena-shy horse, don’t think, “How can I make him get in the arena?” Think, “How can I make it uncomfortable for him not to go in the arena?” You’ll do that by working the horse hard where he wants to be (outside the arena) and letting him rest where you want him to be (in the arena). You’ll do the complete opposite of what he is expecting.
Depending on how arena-shy your horse is, you might only be able to get him within 150 feet of the arena before he starts misbehaving. That will be your starting point. Using one rein to direct him, you’ll work the horse hard hustling his feet and constantly making him change directions. The more you change directions, the more he’ll use the thinking side of his brain.
Work the horse for 15 to 20 minutes away from the arena and then take him into the arena and let him rest. In the beginning, you might only be able to bring the horse within 90 feet of the arena. While the horse is resting, rub him and give him a chance to catch his breath. After letting him rest for 10 minutes, go back to working him 150 feet away from the arena again for another 15 to 20 minutes.
Each time that you work the horse, you’ll take him back to your original starting point – the place he wants to be. And each time you let him rest, you’ll bring him closer to the arena. The second time you might get him 60 feet from the arena and the third time you might get him in the arena.
When you let the horse rest, drape the reins down his neck and dare him to move. If he wants to move, let him. Take him back to where you were working him and hustle his feet. Instead of sitting on the horse and saying, “Don’t go!” let him move, and then offer him the chance to stand still and relax. You have to give him a reason to want to be in the arena and to relax.