“For the execution of any movement, it is necessary to use action and position:
action is the result of the force that drives;
position is the normal weight distribution necessary for the requested movement.
If the action and position are right, the movement is also.”
~Baucher on his second manner (translation Craig Stevens).
These are the physical and psychological components to working with the horse. Consider that they are born of the mind and manifest in the body. The common consideration is only to examine the physical. That is a mistake.
Kindness brings a favorable position of the mind and action is the impulse to dance in harmony with the motion of the horse/rider ensemble. This is simple enough, and so basic it is forgotten.
Always train the mind first.