For me it's my mindset. I keep a strict log of my weight lifting progress so I can see results on paper and that helps me to keep going because eventually (and already have) I will see my physical results.
As for eating I am not as strict and as a result I can tell I am not making progress. Having muscle mass in the upper and lower body is awesome but I have a little man-belly....ugh.
It is not okay for an alcoholic to get drunk once in a while.
So do not tell a food addict it is okay to eat like sh*t once in a while