I allow myself one freebie/"wild-card" a week to have whatever I want. The idea is that you don't have to deprive yourself of stuff you like - you just have to keep it in check so you're not having junk-food every night for every meal. I just keep going until the next Sunday, and then I have a new wild-card to use sometime in that week. You can use it on a dessert, a meal, whatever. Just keep it to once a week.
Last night after Valentine's Day dinner, we had the chocolate-explosion cake w/ turtle ice cream & whipped cream. We shared it, which is better than me eating it all myself, and it was my wild-card for the week. So, I just have to stick it out until Sunday. I'm finding those Sundays come sooner than you think, so just be strong. (I'm also starting to find that those desserts and hamburgers aren't worth it half the time. Funny I never noticed that when I was packing them away on a regular basis).
If you're good 95% of the time, and don't get hung up on "cheating" and "throw in the towel" you'll still make progress. I don't consider it "cheating," because that implies I did something wrong, but I didn't do anything wrong. It was part of my eating-plan!
Although I did feel guilty enough that after dinner when we went home, I did 30 minutes on the treadmill and some crunches... but I was contemplating doing those anyway, even before the cake...
--Janis