The guide being an ace with the GTD technique is some thing the book answers quite well at the end of it. Its a thing called 'Constancy of purpose', its simply

The guide being an ace with the GTD technique is some thing the book answers quite well at the end of it. Its a thing called 'Constancy of purpose', its simply a way of saying you can be productive, only if you do work that is satisfying to you. Once you find such work, and you get drowned by it, GTD helps you be organized and work through it in sanity. The problem for most people is working through boring drudgery day in and out, until boredom becomes routine. Brain begins to largely see what it has memorized as pointless to be played out on paper, and sooner than you realize you drop out of GTD. So to an extent you need to be doing new, exciting and at least satisfying stuff to get your GTD regimen going. Once you are involved with such work. GTD is plainly simple. Just list out all tasks in the order of urgency and goals. That is life, decade, yearly, monthly and weekly goals. Then at weekly level, write down stuff and prioritize them. Anything that can be addressed in 5 minutes, just do that right then. Other stuff goes in the order of priority. You review your list every week, and lastly the important concept of deadlines. Once you commit to a job, finish it within a timeline or it becomes irrelevant after a while. The other stuff to GTD is your regular discipline of being motivated, focused etc.