There's a phrase, "sitzfleisch", which means just plain sitting on your ass and getting it done. Just showing up for work. My uncle Raphael was a painter, and he used to say, "If the muse is late for work, start without her". You have to be there. You have to be there, and do it, and grind it out, even when it is grinding and you know you're probably going to rewrite all this tomorrow.