(this tip works with finances too)

You can give yourself an ability akin to time travel by writing things down first.

If I write down the calories afterwards, I get the "oh, I shouldn't have done that" feeling at times. I'd like a little time travel button that takes me back to before I did, and let me adjust my behaviour and run through the situation again. If I write it down first I get to have the "oh, that's not worth it" feeling up front and decide to do something else.

This made a big difference for me, both lowering what I was eating and making me happier about the choices I made.