This is what it's all about. We don't put up with excuses for why homework didn't get done, or why someone did a poor job at work, or why we forgot to pay this bill or that, so why would we put up with them for not losing weight?
There is a phenomenon in therapy called "Yes, but..." Sometimes I get clients who complain, complain, complain, and every suggestion, insight, or intervention is met with a phrase that begins, "Yes, but..." Nobody gets better that way. Nobody loses weight that way. Honesty with yourself and being accountable are incompatible with excuses.
Relatedly, rationalizing is also a killer. "I can eat this ice cream sundae because I just spent two hours playing basketball." Yeah, but how much further ahead would you be if you didn't eat it?
As is seen in my other posts, I am all about finding what works for you and doing it, and if that includes relaxing or "cheating" once in a while, that's great. But be honest with yourself about the fact that you are doing it, plan for it, compensate for it, don't apologize for it, and don't make excuses for it.
And now that you don't have to be perfect, you can be good.