I always enjoy listening to / reading David Allen's take on the personal world of getting things done. He has a knack for bringing new light to ideas I've heard before. In one of his recent Productive Living newsletters, he talks about the Gestalt idea that The way out is through and provides this simple reminder:
You can only do one thing at a time, so at any point in time there is going to be a huge backlog of "work." Much of what we must do, to gain comfort and control in our knowledge-worker worlds these days, is clarifying what all that work is, objectively, in a format that provides an easy overview.
There are always more things to do. Rather than continually bemoan the fact that the backlog exists, find some mechanism to "gain comfort and control" over what you are doing today and what you are NOT doing today.