I struggle with this a lot too. Sometimes I think: "I Want To Cheat." But then usually a voice in my head will say, "You're only cheating yourself!" So that helps. It's frustrating.
The best thing for me right now is to log on to FitDay. Entering all my food in the program makes me accountable, and when I think about eating something that will put me over my caloric limit, I then think, "But then I'll have to enter it... and I'll feel like a failure... " So then I don't eat it. Most of the time.
Another help is to read posts on here. It helps to read success stories. They are always encouraging. Or really any thread will help because it gets your mind on something other than that treat you're craving, and helps you realize that lots of other people are doing this too, and lots of them are successful as well.
That's my 2 cents.
F, 31 yr old, 5'-6"
Highest weight: 205
Joined FitDay: 8.8.11
Starting weight: 178.0
Current weight on 9.29.11: 168.6
Goal weight: 150.0 (3.1.12)