You have to find something you relate to in every character.
The reason actors are assholes is because they don't eat.
In school I really loved Shakespeare, and I participated in a country-wide Shakespeare competition.
I work constantly to be better at being rejected.
I feel crushingly embarrassed when I do bad work, so being rejected after doing bad work is actually harder than being rejected after doing good work.
I've seen some of my favorite actors give bad performances, and I have to tell myself that failure is a part of success.