Ugh. I know the feeling. I used to really judge myself based on how well I did in school. My self-worth was defined directly by whether or not I got a B+ or better in each of my classes. Anything lower and I'd feel really terrible/discouraged. It was great in the sense that it motivated me to work hard through school but, after a certain point when I developed a medical condition I couldn't keep my grades up. It was a true learning experience to just "let a C go..." and after I was able to do that I even failed a class and more than that I learned how to be happy with putting my best foot forward vs. how the teacher or professor valued my work. It was really freeing to not be tied to grades like that and alleviated a lot of my depression issues when I stopped worrying so freaking much.