One thing that is critical for me to stay on track in to make sure I always have an abundance of primal foods around. If I let myself get really hungry and have no good food available, I'll eat whatever I can get my hands on.
One tip I got from nomnom paleo is to make a big batch of what she calls "emergency protein" and package it in to single serving and freeze it. I always keep some frozen veggies on hand as well. So if I am running late or was disorganized or lazy then I can always thaw the meat and heat some frozen veggies and have something to eat.
I also have a rule that I won't eat two non-primal meals in a row. So one bad meal is never a risk of turning in to a full spiral out of control.