Everyone (including myself) always forgets that they have a life to live too. It's okay to go off plan or skip every once in a while. Obviously don't eat ice cream 5 times a week, but also don't allow negative self talk allow you to think you're a failure because it's "bad".
It's easy to overestimate what you can do in a day, and underestimate what you can do in a year. One mistake or deviation doesn't define you!