While I agree that a book can't magically create motivation, books (like conversations with people and new experiences) can help you discover what makes you tick, provide new lenses through which to view your world, and open you up to new ideas. Using a book to help find what makes you tick is perfectly fine, and using a book to learn new ways to focus/stay focused is definitely fine. Use that library card...if one (or a dozen!) doesn't resonate with you, return it and grab something else with no money sunk into it. Explore and enjoy the journey.
For what it is worth, every year, I think about what I want my life to be like in one year, five years, and 15 years. Maybe use that that in conjunction with working through what @James Mc Ree suggested. I am not primarily motivated by money either--I would not work at a soul-sucking job solely because it paid a good wage. But I have realized that the things I want to do in five years and 15 years, the opportunities I want to provide my kids, and the level of involvement and impact that I want to have in the community can all be more easily achieved and better implemented with good income and a comfortable slush fund. The money is the enabler to make the things that do motivate me (traveling, working with children, etc) a reality.