Permission to Write Crap

I am struggling with the fact that I can not seem to give myself permission to write any old thing for the first draft. I struggle over each scene and can't go on untill I feel a sense of satisfaction with all that has come before. As I get further into a WIP that becames harder and harder and eventually I put that WIP aside and move on to something else. I know I will never finsih a novel that way.