I watched a demo about this just last month by Jonathan Fields - he spoke a lot about how you have to create "draw" and "push" (I think that's what he called it, it was something like that). You create "draw" through groundwork exercises which teach the horse that there will always be a spot that you want the horse to be in, and when the horse finds that spot (whether it be standing on your left side, trotting a circle around you, standing in the far corner, etc) then your body language should be rewarding the horse, if he is not where you want him to be then you tell him through body language that he needs to find that spot.
Heck if I can explain it very well, though lol. That's why I am NOT a clinician.
. It made sense to hear it while you saw him demo it. I also have yet to try it.