The OrganizeIT weblog has a post that outlines what they consider to be the four stages of productivity as it relates to GTD:
OrganizeIT takes the ideas outlined in “Your Best Year Yet,” by Jinny Ditzler and integrates them with GTD. OrganizeIT does a very nice job detailing what specifically happens at each stage of the cycle.
The book doesn’t go into much actionable detail…so I’ve decided to take the basic principles…and make it more GTD related. The diagram…is broken down into 4 sections – plan, do, complete, reward – which I have gone into detail below.
The Productivity Cycle – [OrganizeIT]