I don't know why you think you don't fit in.

Grades are important, but I guess I don't feel the anxiety as my grades are all very high. I do feel pressure to get high grades, especially since I am older.

I do judge both the seriousness/passion/ambition and the intelligence of my peers partly based on grades. I mean, that's the main reason we are all there, right?

I myself always have to be on my guard not be appear too arrogant. I have impulses to act arrogant and I don't always notice it is apparent to others that indeed I am.