I think NH is about using the horse's natural instincts to either move him away , or bring him in toward you. You use his responsiveness to pressure to have HIM make the desired moves. So, the idea is to engage him mind and have him making choices; to come toward you or move away , to step his hind away, to face you and stay connected, or to move away from the pressure that you apply, and this need not mean even touching the horse. It's about creating a "feel". That can be some energy going down a rope, it can be your pressing against the air, and thus sending energy toward the horse. It can be very little, and that would be optimal. Since the object is to have the horse make the decisions based on your Prompting, having him do so with as little pressure as possible keeps him engaged, rather than simply doing what he has absolutely no choice to avoid.