I think that one of the most relevant lessons I've learned this year is that no one really cares.
There isn't any use in constantly complaining about your life to other people; 87% of the time they couldn't care less.
Don't be constantly self-conscious. No one is judging you, they're hardly even paying attention to you at all.
You can't expect your friends to do anything for you. Most people won't drop everything for you, so don't set yourself up for disappointment.
It's just one of those things in life that you can't avoid. Everyone is selfish, and that's a fact. So stop worrying about what other people can do for you, or if other people like you. Ultimately, the only person who will always be there to take care of you is yourself. Learn how to keep yourself in line. Teach yourself how to be happy. Because if you don't care, then absolutely no one else on Earth does.