Well pick one change you like to make. Just one. A piece of your diet, exercise, whatever. As long as you do one. Then as your doing it, and every time you do it, say something to yourself like “i love this” or whatever you want. Try to keep this up as long as possible. So I would suggest when you have one of your lucky streaks. Then when you don’t want to do that, say the phrase to yourself. It will make you want to do your thing again.
Like I said this works for me because I was so determined in the beginning to go, I knew myself. I was just like you where I didn’t want to do it all the time. Then I came up with that and I’ve been weight lifting ever since.
And I say make one change at a time. And when you’ve mastered it and it becomes habit, you can congragulate yourself and make a new change and start the cycle all over again. Eventually it will pile up and you’ll be a new person!