When Milton begin to work on a book, he writes, writes, and write some more until he's ready to publish. He set goals for himself to work towards them til he complete each goals. How does he complete them? Well he completes them by staying focused and not letting anything or nothing to get in his way of what he is trying to do and accomplish.
For him to stay motivated, is by having a personal relationship with God of which he is able to go further than he could ever think of or imagine. He makes sure he surround himself with positive mindset people, by listening to gospel music, reading the Bible, and reading positive quotes that helps him to stay motivated.
If you want to see how your life would change, purchase his book Walking in God's Path Toward your Destination Vol. 1 To Change Your Mindset