The thing about humans that often makes their work with horses ineffective is that humans are always living in the next moment; at least in the next moment, if not one five years out. Get the bridle on in order to ride, turn the horse out in order to get home
Horses are all here and now, although they will remember if you've been an ass (or nice). They think how you put the bridle on is just as important as what you are going to do later with them in it. If they disregard you at the gate and tear away from you before you even get the halter off, they disregarded you long before that and they will continue to the next time they see you too.
The thing about horses and humans is that sometimes, rarely, a human may help a horse heal, but the horse pretty much always heals the human, and I believe that is the result of the horse requiring the human to be fully present in the here and now to be at all effective with that horse. Also, to be effective with horses you can never lose your temper, you have to take what you get today, you cannot take it or mean it personally, and you cannot be impatient. All make for a better human being.