"And by the way, everything in life is writable about if you have the outgoing guts to do it, and the imagination to improvise. The worst enemy to creativity is self-doubt.”
-Sylvia Plath

At the risk of sounding too inspirational, I think this quote can apply to a lot of different things. Everything in life is doable if you have the outgoing guts to do it, and the imagination to improvise. The worst enemy to anything is self-doubt. I know I need to be reminded of this daily.
Also, I love Sylvia Plath. I want to be her, minus the depression and suicide.
And Ted Hughes cheating on her.
Everything else, I'll take. Especially her poetry. Or prose.

Anyway, I think that writing, like anything else, is all about striking a balance between confidence and criticism. You have to have both--confidence especially helps me start anything, and then criticism helps me keep it in check. It's easy to spot people who have an excess of one and too little of another. People who don't know how to edit have too much confidence, and people who edit and question themselves too much have too little confidence.