"All or Nothing"is not your friend
I often talk with clients who have an "all or nothing" mindset around food.
If you tell me not to eat something, I won't. I'll have none, zero. But if everything is acceptable in moderation, I'll enjoy a treat, then beat myself up for having it, and go on to eat as much "bad" food as I can for the rest of the day because I've already ruined it, so why even try?
Or, another very common one is the phrase "I'll start Monday" - that might mean eating healthier, cutting sugar, following a "diet" but it almost always means it gives me the excuse this week to eat whatever I want.