This is something I've noticed, too. In my GTD system for a long time I let past due actions sit, on the theory that eventually I would do all these things that went past due because I would feel the pressure. Didn't work. What does seem to work, though, is negotiating realistic due dates with myself. If I set a date by which I want to do something and it doesn't get done by that date, then either I need to do it right now or it was something that really could have waited until later, so I renegotiate the due date with myself. I'm not a total expert at this yet, since I tend to do a lot of renegotiation, a task which should in theory be rare, but so far it seems to provide a real help in that I'm not constantly looking at things that don't actually need to be done right away.