In training, we use both physical and psychological pressures to shape the horse's behavior. Every training activity needs to be structured in such as way that the horse himself removes the pressure when he provides the correct response. He must feel the pressure as a solvable problem, as something that goes away when he takes a certain shape.
When the horse is aware of the pressures but remains relaxed and breathing rhythmically, the horse is in a learning zone. You want to keep him in that zone all the way through anything you're teaching him, regardless of how energetic the activity is, regardless of how complex it is or how often you want to change the activity. If you can keep the horse in that learning zone through the whole training process, then what you'll wind up with is a super performance horse.
In order to get a horse into that zone and keep him there, the first big lesson he has to learn is that he can trust us. We want him to feel absolutely confident that we will never introduce something that's going to hurt him. We will not make big, sudden movements. We will not scare him with a big psychological pressures. We will always give him hints and cues in advance of asking him to change the shape of his behavior so he'll never get surprised and so he can respond successfully in a way that rewards him for the change.
The way to build this level of trust when you are training a horse you have to remember two things. Never ask anything that's more than one step away from what the horse already knows and never force the horse out of his psychological comfort zone. You need break each thing you want the horse to learn down into very small pieces that you introduce one at a time so you can always control where the horse is psychologically. If his actions and posture tell you he's starting to ask himself "What is that" or "Is that safe" then you need to back down to where he is comfortable, go back to building trust with things he's already comfortable with, and try that new little piece again later. If you force the horse beyond his psychological comfort level, what the horse learns is that whatever you were asking him was scary. If you force him into accepting that new step before you put him away because that's the lesson he was supposed to learn that day, you're breaking him, not training him.
What we want to do is train him to trust us and to accept us and to accept all the things we ask him to do as safe. That is a subliminal message that he learns over a long period of time so that when the day comes that we ask him to walk into a trailer or walk across a creek and we say it's OK, he accepts it as OK.
As an example, I see a lot of baby horses accept the saddle when they see it. They stand there perfectly alright until you raise it up to eye level. Just at the time you start to go above eye level, they start to be worried about it. So that means that you go an eighth of an inch above eye level and then you go back down. You don't try to trick them into tensing up and just standing there while you try to slap it on and then hope you can get it strapped on before they start jumping around.
If your horse gives any sign of getting nervous when you start to go above eye level with that saddle, what you do is drop it back down and let him know that nothing was scary about it. If you got too far and his attitude changed before you recognized that he was getting concerned or frightened, what you do is back all the way down to what he was doing before you started showing him the saddle to get him back to rhythm and relaxation in his work.
So you would hang the saddle back up and go back to quiet longing anywhere until the horse is rhythmic and relaxed and you stay with that until you have the rhythm and relaxation again and then you try the saddle again, maybe on the other side and see how high you can get with it there or even how close you can get with it. When you come at him the second time with the saddle you may find that he'll really be worried about it now. If that's the case, as soon as you get close enough that he says "What's that" you stop. You wait there until the horse either comes up to the saddle or finds something else that he's interested in or you lay the saddle down and go over and give him some scratching and loving. After awhile you move the pressure again.
Things start to go wrong when you assume the horse will understand something that's more than one step away from what he already knows. You can't assume that if the horse says "This is OK" he'll be able to make the connection that if this thing is OK, then that thing will be OK and that other thing's OK, too. Horses don't relate activities that way. They can't take that big a psychological bite.
The way a horse thinks, anything sudden or anything unusual is dangerous. If you apply sudden pressures that the horse did not anticipate, you are only going to elevate his excitement level and destroy any relaxed feeling between the two of you. Those pressures are going to interrupt his breathing rhythm, spoil his understanding of what you're trying to teach him, and push him out of his comfort zone, out of his learning zone. So it doesn't matter if the people next door think you could have been riding on him by now. It also doesn't 't matter if you quit trying to do something today because the horse was afraid of it.