Mike Kaspari has a detailed piece on procrastination. The basic ideas he proposes to break procrastination streaks are solid advice. For example he proposes to start with a burst of timed activity (even if it’s just a 5 min burst). He recommends writing a list of reasons why we are not doing that important task (and looking at how silly they are). An interesting one is that he advocates getting together with your buddies to do a “writing fest” before going to lunch, and use social pressure to get some writing done.