For this I like to describe it as "cues" and "aids". The "aid" is what you know
already works to achieve a certain movement, and the "cue" is what you want
to work to achieve the same movement.
As long as the sequence goes: 'cue followed by aid', then eventually the cue will become the aid, in which case you could settle with that or find a new more subtle "cue", and use your previous cue as the "aid". That sequence of constantly refining your aids can continue untill you have the same sort of "control" over your horse as you would any muscle in your own body.
An example would be if you wanted your horse to turn from neck rein pressure. The neck rein is the "cue" and whatever you already do to turn left is the "aid", if you consistently follow the sequence of cue then aid soon enough the neck rein will function as the "aid"