delays

Is it a case of laziness? Writer's block? The shock of having no papers to grade today? For thirty minutes I have been trying to begin the day's writing. My plan is to spend half my workday hammering away at an article, a piece I care about deeply, a piece I have been working on for some time. I have a very positive 'revise and resubmit' letter from a good journal, so why can't I get started? I have specific suggestions from reviewers, some messy notes toward revision, and motivation. Smokey's sleeping on my office futon. And I know that with 4-5 hours, I can, theoretically, do quite a bit. What do you do on days like this?