Hi George;
Best of luck to you, as you "begin again" with GTD...I started my GTD journey in 2014 and I know it is not one that follows a "straight line"...it is soooo easy for me to slack off, and/or partially utilize GTD.
Not sure if this is helpful, but I have found reading other "philosophies" very very helpful to me, as I dug deeper into why I could not stay with GTD for very long..."The Power of Habit" (C Duhigg), "Willpower" (R Bauermeister), and "Deep Work" (C Newport) are a few books that GTD lead me to, and that I found very very helpful in self-diagnosing why I just could not embrace and put GTD to use 100%.
Looking forward to hearing how you are doing, as you jump back into GTD, and Congratulations on bring it back into your life!