Thanks for sharing this article! While I don't agree with everything in the article, I can certainly agree that there are three distinct components to success with GTD:
A) Learning the functional components of the GTD methodology.
B) Developing the habits (automaticity) needed to make your productivity system (based on GTD methods) consistent and less work than maintaining it.
C) Learning your home and work skills. GTD cannot ever teach you how to do what you need to do, nor can it do it for you. That takes intrinsic motivation and hard work to learn and hone those skill sets.
Sadly "C" is not something GTD or David Allen has any ability to quick-fix away the challenges someone implementing GTD may face. You just need to learn to motivate (ergo, thought into action) yourself; of which, there are many strategies and tactics to achieve this. :-) Thanks for getting the gears moving on this important facet of GTD!