If you get off track in the middle of the day, don’t tell yourself, “I just won’t eat anything else for the rest of the day.” That never works. First, because that's punishing yourself and if you get off track you don't deserve punishment. Second, if you think, "I shouldn't eat anything else," and then feel hungry later, you may get anxious and then think, “This is just too hard. I’ll keep eating whatever and get back on track tomorrow,” and then wind up overeating and taking in way more calories than you would have if you had decided to just have a reasonable dinner.