I answered this for someone on Litreactor recently: I don't get writers block so much as writer's frustration. I always have something I can work on, or some idea I can try, but the frustration comes when neither seem to work for me and that's when I say 'Just keep going.' I once told a friend of mine 'thanks for all the help but I'm binning the book' only to tell her half an hour later that I'd had the one idea that I thought could save it. It did, and I now have Shadow's Talent published, two years later. Telling myself there's no such thing as a story that can defeat me works.