I don't think your problem is motivation, but execution. And, yes, if you haven't read the book, then do.

Then just keep it very simple to start with:
1) Get a physical inbox (only one) and put every list and scrap of paper and everything that you feel you want/need to do something about in it.
2) Take two sheets of paper and a pen. Write "Projects" on top of one paper (this is your projects list) and "Next actions" on top of the other (this is your next action list).
2) Take one item from the inbox at a time. Decide what "done" means (what is the outcome you want to see true about it) and what the next step you want to take to move in that direction is (this is your "next action").
3) Write down the outcome on the Project list and the next action on your next action list. If you need to, put whatever material you have relating to this "project" in a folder and put the folder in a pile that you call Support material
4) When you are finished emptying your inbox, have a look at your Next action list and see if you want to rewrite the list with subsections for Errands, Phone calls etc. (but only if it helps you)
5) Start doing what is on your next action list starting with the thing that you feel would give the biggest payoff. Check off when done.
6) At least once a week (and more often if you feel you need to) go through your project list and next action list and make sure it is current and add new stuff to your next action list as needed.
7) Always carry a small note book to write down new ideas and thoughts. Start again at step 1.

Then, make sure you make it a habit by being very strict about it in the beginning and set aside plenty of time to practice being thorough doing all the steps. And re-read the book.