Focus, focus, focus

Ever have so much to do that even when you are working on one task your mind skitters among all the rest? I've yet to learn how to stay focused on the job at hand, and instead of reducing the number of things I need to do I seem to be increasing them. Some are unavoidable, certain circumstances at work require that I add to my assignments, at least for a time. Some are just by inaction, a number of tasks could be done and out of my mind and hair if I'd just do them rather than thinking about doing them.