Daily PlanIt has a simple but effective chart on how David Allen's concept works. I've learned a lot about myself and why I do things in a certain way by reading David Allen's Getting things Done.
My whole way of thinking has changed for the better. I can't just sit idly by and not do that next action that I know is only going to take a couple of minutes. I look at my projects with fresh eyes, trying to break them down into next actions which may not take a lot of effort on my part, but yet still keeps the project moving along to completion. This enables me to have several projects underway, all progressing and not stagnating.
I have only scratched the surface of GTD, and have more to learn and implement, but it's not a race...it's a lot of do-able next actions.