The surest way to mess up someone’s mind is to force them to do something that they already want to do. Or to forcibly prevent them doing something that they don’t want to do. Either way, they have to make an intolerable choice between submitting to force, or acting against their own will.
This is the essence of insanity, this is a double bind. As L. Ron Hubbard said in one of his better moments, fundamental aberration is the enforcement of basic truth.
But the converse is also true. If your mind is doing things outside your control, for example bringing up unwanted images or emotions, the solution is to do deliberately and consciously whatever the mind has been doing automatically. This will bring that automaticity under control so it can be used, or not, as appropriate. If someone is haunted by an unpleasant memory, they need to recall that memory by their own free will until its apparent power over them vanishes.