In my experience, if you figure out which cheat foods head you down the path to your old food habits then you have to avoid those foods. You can’t have them in the house at all.
I’ve stayed on healthier diets for months, sometimes years, at a time, but never acheived a permanent new diet, so maybe my opinion shouldn’t count.
I say do changes over time. Maybe at first you eat more vegetables. Then you cut out some cheese. Then use a little less salt. Those are just examples, I don’t know what you need in your diet. Your tastes will change if you stick with it.
For a few years I ate no dairy. I was having a dairy intolerance, it sent me right to the bathroom, but that was the worst of it. When I stopped eating dairy I lost weight, felt better, and my cholesterol went down. I really should do it again. My dairy intolerance eventually got better, and I’ve been eating dairy for years. I started trying to limit it again though. When I was cold turkey I even ordered pizza no cheese, and I love pizza.
Cooking from scratch helps me. I’m lazier about cooking as I’ve aged, and the healthier foods happen to be less work for me from scratch. That just happens to be the case. My salads and veggies have less clean up than pots and pans from the stove top and oven. Meat has more to worry about when preparing. I find it more time consuming, and more to deal with.
I find cheating once a week at a restaurant doesn’t mess me up, but eating out a lot does. Also, cheating at home sometimes takes me completely off track and back to old ways.
My grandma told me in her 40’s she just started picturing bad food as poison, and would leave the table feeling not quite full. She said it took about three years, but finally that smaller portion (fewer calories) became normal. She kept of the initial weight she lost in her 40’s for the rest of her life. She had lost 20 pounds. Her upbringing her mom had encouraged her to be plump. Although, by today’s standards her plump would be average. I’d say she went from a 12 to an 8.