I used to get really stressed if I missed a workout or binged on pizza, but what got me through it was telling myself, "So what! You have eaten well for two weeks without falling off the wagon, and you've worked out every day for the past month. This one little thing is nothing compared to all that." By focusing on all the good stuff I'd done, it put the bad stuff in perspective..and I stopped obsessing about it.
Nowadays, I actually put a "free day" in my week where I allow myself to eat whatever I want to. It's a lot easier to make through just 6 days to get to a free day than it is to pressure myself to "never eat anything fattening again." I mean, I love my pizza, my onion rings, and my Dairy Queen Strawberry Cheesequake....so, rather than punish myself for the rest of my life, I allow myself to indulge in these things one day a week if I want to. And, if on my free day I don't feel like indulging, I won't...which is okay, because one day in the following week I might get a craving and I won't have to feel guilty over ordering a pizza. What's more, I have found that I've lost more weight by doing this than by shunning fats altogether "forever and ever."
In addition to a free day, I MAKE myself not exercise one or two days, depending on how I feel that week. I absolutely will not beat myself up for not working out, because I know that for 5-6 days that week, I will be working out, and that my body needs to rest and recover, anyway. I always find that if I take a week off, I come back more rejuvenated and stronger into my workouts because my body has fully rested and recovered. I always build a week break into between my rotations. I'll go for 12 weeks, then break for a week, come back for 12 weeks, then break for a week. At the end of the 12 weeks, I feel a little burned out, but I find that by the end of that week off I'm chomping at the bit to start working out again. It really recharges my battery.
Sorry this is so long, but I hope it has helped you.