Okay. It was one day. Choose to make today different.
+1. You can't undo yesterday, so there's no need to dwell on it or to beat yourself up or to use it as an excuse to be over today. Be intentional today.
I know it sounds hokey (think Stuart Smalley), but have you ever tried a mantra for yourself? Something along the lines of "I'm worthy, I'm loveable, and I deserve to take care of myself through good food and exercize choices"? Say it to outloud three times in a row every day as you look at yourself in the mirror. It will add all of about 10 seconds to your morning routine. You'll eventually start to believe it and will then make better choices for yourself.