Never respond to rudeness. When people are rude to you, they reveal who they are, not who you are. Don't take it personally be silent. For more quotes and inspirations: http://www.lifehack.org/articles/communication/never-respond-rudeness.html?ref=pp
Ask yourself this when someone says you can't do it. What's holding you back? Exactly. Nothing but them and you, but only because you are letting them.
Dear Self. You know what they say about perfectionism...don't you? Why you don't have to be perfect, and in fact it's necessary that you don't try to be.