Some people have chemical differences in their brain that impairs their ability to be, well, like everyone else. Maybe some people pretend they have OCD. Maybe some people are depressed simply because they won't try to get over their sadness. But sometimes you really can't help it, and finding out that other people are like you, can help.
Here, you want a personal story?
I have social anxiety.
It's not diagnosed (why would someone with social anxiety want to talk about it in person to a doctor?), and it's mild, I guess. Usually just knowing that people won't judge me as harshly as I think they would helps. But not always. Unless I'm fully confident about what I'm doing, I won't do it. It's awful going to my church's choir practice, offering to sing the alto part, and mumble the entire time because I'm used to soprano. It's generally (there are exceptions) awful being around people my age. They can be so...bold, in a way. Very overwhelming.
But the brain is an amazing part of your body. All parts are, but the brain is what can make you think that your brain is amazing. It's kind of funny that way. :)