Don't major in the minors or sweat the small stuff. One missed workout is not going to make or break you.
One day off your diet or nutrition plan is not going to completely derail your goals.
Focus on what you do the majority of the time and give yourself the space and freedom to go with the flow the rest of the time.
Whether that's 90/10, 80/20, or even 70/30, find what works for you.
Don't miss out on 90% of your life to progress 10%.