Unsolicited tip. Something I find has helped me a lot with challenges like you are facing is to stop looking at them as difficult or choices and simply understanding it what you have to and are going to do. Remove the choice from the equation. I had some pretty destructive habits when I was younger and now people comment on my strong mental discipline. This approach has really helped. I recently had to cut all starch from my diet due to an auto-immune diagnosis and went through ketosis. The discipline has now become the habit. It never occurred to me to not follow through even in the deepest keto flu period. It's possible to achieve and once you've beaten one hurdle the next one becomes easier until you control fully your thoughts and not the other way around.
Definitely second this. Choices are hard, but decisions are easy. If you make hard rules for yourself and decide to follow them without exception, it is much easier to stick to, at least, that's what i've found for myself as well.
Interesting. I will try to think that way. BTW I’m quite self-disciplined pretty much every other way and I never thought much about it, but I think that’s how I normally am. If it’s not food or caffeine...