The mental model you have for yourself is more important than you may know. When you tell yourself, “I’m the type of person that ______.” Your body and mind come into alignment and more often than not you do or don’t do something.
Think about cocaine, maybe 2% of Americans do it recreationally, so chances are, you don’t. Even if someone offered it to you, you’d say no and that would be it. Why? Because you don’t do cocaine. Soda? I don’t do soda or cocaine for reference. I have, and as a Public Service Announcement, I don’t recommend anyone starting either one.
When someone offers you cake, candy or whatever, you can start saying, “I don’t eat _____,” if you want. You can even try it out and play with the details. I don’t have more than 500 calories from added sugars a week so I can be a little flexible with my ice cream or candy consumption but certain things, like sweetened beverages, are almost always going to be a no for me.