One of my favorite quotes is "The Man in the Arena" from Theodore Roosevelt's Citizenship in a Republic speech. I first found it from this great TED talk about vulnerability.
It's so easy to criticize other people's effort for anything from a selective internship to a theater group to relationships:
"Can't they see that x won't ever happen?"
"(S)he'll never be able to work as a x"
"Why are they bothering?!"
Almost unconsciously, it's easy to start to see things "objectively". Yes...that person may not be the best, most accomplished singer/best internship candidate/his normal type. It does seem like a waste of time for to even try, right?
"Being objective" doesn't seem so destructive until it happens to you. When you are an imperfect human being who fails in public, people will come out of the woodwork to tear you down. Sometimes, those critics can be the people once trusted, making it worse.
When this happens, I try to remember this quote. The man in the arena shouldn't worry about those who don't even bother to get down in the arena. (Personally, I find the people who hang out in the arena much cooler anyway!) And I have to try to not be the critic when I see others fail.