How to keep motivated?

I'm wondering what the best way to stay motivated as a writer is. It's easy sometimes, on the back of a success to keep writing and sending out work. Likewise when there is a deadline involved, a new book in the post, a new project, a pat on the back still making your writer faith tingle. Other times its less easy. How does a writer keep writing when self doubt rears its ugly head? I hate to say it, but several people this year really destroyed my confidence. Everytime I sit to write a poem I remember. Likewise, when I sit to consider sending a poem anywhere I can't do it. I'm scared of abuse. If any writer told me this about themselves I'd say- Send work out NOW. Get back on the horse. Get some acceptances, positive comments to balance the negative out. What I'd say is prove the fucker wrong.
How to do it though, start, to get the faith back, love poetry and live with it again like I did for so long, I really don't know. Starting is thing.