For example, stand at the horse's front legs with your belt buckle facing its shoulder as you scratch the horse. Continue to keep the line through your shoulders parallel to the horse's body all the time you are scratching and rubbing him. If you find a place the horse really likes being scratched, you have his attention on you. Your goal is to captivate the horse, to keep the horse heeding everything you do, paying attention to everything you do. And everything you do, you do in a perceivable pattern with a calm attitude.
Horses only pay attention to one thing at a time.
Their eyes are out on the sides of their head to see any approaching attacker and their instincts tell them to constantly look out for those attackers. This superb peripheral vision is what makes it so easy to get horses to heed your body position. They can see all the way to the back of their hindquarters with just a slight tilt of their head. But what gets their attention keeps changing all the time. When their attention goes away from you, your goal is to get it back.