Whenever you're feeling sad just let all the feelings flow. Let your self know that whatever you're going through; someone somewhere is facing the same problem. Whatever happens to you; someone will be there. No-one is completely perfect and no one ever will be. Everyone has their perfections and everyone has their imperfections. If you seem full of flaws and disappointments just remember: Someone out there loves you for who you are and they wouldn't change anything about you.
So don't pretend to be something you're not.