Make bad habits harder
Make them impossible. When you have a huge craving and it’s 10:30 at night, if you don’t have accessibility to that thing you’re craving, you won’t get the junk.
Cravings won’t last for ever. Eliminate the opportunity to make them happen.
If you add a hurdle into your bad habit, you’re less likely to do it. Eliminate the accessibility or set yourself a challenge like going up and down the stairs before eating a dessert or crisps; you’ll notice you’re less likely to do it because things are not just there.