They vary, but a common denominator is a happy, healthy horse whose cooperation is voluntary due to:
Relationship. Security in our company; mutual communication; respect for his sensitivities and fears, especially of capture (a.k.a. control by force). Finding these, a horse wants to be with and synchronize with us until this becomes his habitual attitude.
Learning. When the horse has other motivation, learned signals are necessary. Learning is very rapid if we know how to teach.
Physical preparation. For riding, strengthening and re-balancing take years, and should not be confused with pure learning processes.
These three factors interact. If the relationship is inadequate, both learning and physical preparation are very much more difficult to achieve without something going wrong.
* A horse´s aims
Basically, the same. Horses want to be together, fit and agile; they want to know how the world works, to lose their fears and to be able to control their future experiences.
* So where´s the problem?
The predator´s instinct of clutching harder at an animal that´s trying to escape.
The mistaken idea that horses have the same idea of authority that we do, and that they obey a dominant that achieves its position by aggression and force.
Confusing disobedience with not having learned, or not recognizing, the signals we are using
Giving body language signals without realizing it. When body language signals contradict pressure signals the horse will react to the body rather than the pressure. The confusion also frightens the horse.
Not watching, listening or feeling the horse
Paranoia; fear of the horse and of losing control