"Well I've had one piece of chocolate, screw it let me have the whole box"

I'm totally the same way! Once I eat one "bad" thing, I'm always like "oh well, now I ruined everything so I might as well eat an entire pizza". I read a helpful comment that said you should think of your food more like money in this case: just because you spent 20 dollars on a crappy shirt doesn't mean you should spend the rest of your money on MORE crappy t-shirts. Thanks for writing! :)