But lately I've been having more success and I like the story I've generated around it. I'd suggest you implement GTD slowly, in stages, to combat anxieties that you have. In combating an anxiety you need to recognize it, implement a solution, and recognize how that anxiety is relaxed... and replaced with a new layer of them!
Anxiety 1: lack of trust in yourself to do what needs to be done.
This was for me the baseline ambient anxiety. I had originally solved it by abandoning most todo list systems and even calendars so that I could organically ask myself regularly: "what is the most important thing right now". That was a good practice, but many things "slipped through the cracks".
The first practice of GTD is to have a single, "global unified inbox". As I decided to implement this I realized I had collections of half-measure "inboxes" all throughout my life: email, partial todo lists, memory cues, people I relied upon to remind me of things.
So I cleaned that all up as much as I could and funneled it into a single todo list and kept uncovering more of these secret reminders I was keeping for myself. The result was a relaxation of this anxiety through building trust that I was at least adequately in control of _finding_ and _capturing_ the things to do. From that you can build trust that you won't let things slip because you forgot.
Anxiety 2: there's too much to do and I can't handle it
This anxiety was often hiding underneath the first. In times of emergency I could get things done, but without that focusing my needs and furnishing energy... I'd just let things slip and lie to myself that it was "ok, because important things will come up again". This was true, but a half-measure and one that stole from me conscious control of my life.
So the second practice is "organize" and in particular the compelling notion of the "next action". Organize says "regularly look at your commitments and think about how best to think about them" and the practice of next actions says "for any commitment, know exactly what the next, simple, tangible, visible step you could take is".
For instance, I need to get my car emissions inspection updated. I'd sat on that for months because it was both buried in a listing of "car stuff" and was also sort of a big, mildly important thing that was easy to defer. I chose to reorganize it to my "weekly chores" list which I respect as something to review regularly, especially on the weekends, as a mechanism to keep my life healthily managed.
I also chipped off a next action: "research locations for emissions inspections and their times". With this step I located one nearer to me that I had never known before—reducing the activation energy. I got stuck again with my next action "drive there and do the inspection" because I don't drive that frequently. It felt like it was still a "next action" as I saw it as immediately doable with the closer location, but I reorganized it to be on my "list of things to do next time I get in my car" list it became very natural. I also made a note to bring a book so I could resolve the anxiety of sitting there bored waiting.
So organization helps you create systems to manage and encounter your commitments and the design of next actions helps you tactically erode anxieties which keep you from moving forward. It all boils down to "intentional planning" in a lightweight way.
Anxiety 3: this all takes too much time and I'm slipping
This is something close to where I am now. Relaxing the first two anxieties has already been a big step, though. Here, I am realizing that I have to reconnect with the notion of "letting go". If my system is too big for me to handle it then I'm either (a) not investing enough time in what's truly important in my life or (b) trying to have my cake and eat it too.
Automation and schedule can help. I collect regularly, organize daily, and review lists on weekly, biweekly, or monthly schedules. Omnifocus helps with this by making the schedules something I can forget about and rely on the system to handle.
But what also helps is recognizing things that are just aspirational projects and launching them off into the future as opposed to hanging on to them and feeling a little regular guilt as I choose to do something else instead. My attention and energy are limited—I need to be thoughtful about what projects I am truly engaged with.
"Snoozing" big ideas is another practice to eliminate this anxiety, but the latter one seems more important. With limited bandwidth, I have to be conscious about what I really want to achieve and, finally, choose actively to focus my energy there.
To some degree I feel this is the ultimate aim of any "system".