1. licking its lips,
2. lowering its head,
3. blinking its eyes,
4. cocking its hind foot, and
5. shaking its head.

This is important because once the horse shows a sign of relaxation during a training session, you want to stop applying the pressure.  In other words, stop doing what you are doing and praise your horse.  One method of desensitization is the human currycomb.

I am going to describe the human currycomb step by step. If you are tall enough to jump on your horse, you are good to go. If you are shorter, like me, you need a stool. First, jump up and down while patting all over the horse’s back, including their withers, ribs, butt, etc.  Keep on until your horse just stands there. As soon as they do what you want, stop applying the pressure. In this case the jumping and patting are the pressure.

Now you jump on their back. You are laying across their back with your hands down one side and your feet on the other.  Move your arms and feet like scissors. Pat their belly if you can reach. Again you are waiting for them to relax. When they do, stop what you are doing. Slide off the horse.

Now jump up and swing your legs to the back.  You are now lying straight along its back.  Move your feet to see if your horse is still relaxed.  Now slide off the backside of your horse.  You can have a spotter to make sure that you won’t fall.

This is the human currycomb.  It teaches your horse to stand still which is an invaluable skill to have when one is mounting, sitting in the saddle, grooming, etc.  It also teaches your horse patience.  Now that you have done it on one side, you must do it on the other side.