Along these lines, I once heard somewhere that people do not process the word 'dont'. As a coach, I've had to shift my vocabulary to focus on the 'do's rather than the 'dont's

Eg: If you're doing a sport where leaning forward is bad, avoid telling yourself 'dont lean forward' as your mind only hears 'lean forward', therefore reinforcing the thing you're trying to avoid. Alternatively, tell yourself 'lean back' or 'stay straight' or whatever you're focusing on for that maneuver or drill.

Interestingly I've found this same approach from good coaches across completely different niche sports. I imagine this phenomenon has been discovered a number of times by various smart people. It certainly wasn't intuitive to me, but since learning to use affirmative advice in real-time sport situations, my advice got noticeably more effective.

My karate sensei has a terrible habit of showing how not to do things more than he shows how to do them, drives me crazy.

Huh, the yoga teacher whose channel I'm subscribed to uses only "do" statements - didn't notice until you pointed that out.

Easy, after first imagining the pink elephant you aren't supposed to.

If the first thing that comes to your mind when you hear "imagine a non-pink elephant" isn't either a pink elephant or "WTF, how is a pink elephant?", then you are in a very small minority.