Anthony Trollope

"My belief of book writing is much the same as my belief as to shoemaking. The man who will work the hardest at it, and will work with the most honest purpose, will work the best"

Also, Tchaikovsky:

"We must always work, and a self-respecting artist must not fold his hands on the pretext that he is not in the mood."

I'm not given to pasting aphorisms all over the place (though I do have "Real Artists Ship" on the wall in my studio), but an occasional nudge from that dude probably isn't a bad thing.