I have little to wonder about the effects of books. They work, if you make them work. YOU are the cooperative component, the book just relays information. At the end of the day, the book doesn't do the "work" for you.
What we see today as been heavily influenced by books I read in 2013. Mastery by Robert Green laid bare the path to mastery. If it wasn't for that book I would've never gotten my Expert level in KM. The luck factor by Brian Tracy shined light on the principles of success, with great exercises. The power of habit helped me breakthrough rewriting behavior that seemed impossible to change
Creating an Unshakable character and the day that turned your life around by Jim Rohn. The Science of Self confidence and Miracle of Self discipline by Brian Tracy These are all in the same vein and the same red thread: improvement of the Self. For someone coming from extreme low self esteem these books helped put down guard rails do that confidence didn't turn to cockiness or arrogance. Though the arrogance part seems to bubble to the surface here and there.
Mindset by Carol S Dweck showed me a real profound hope to live a better life by changing the perspective of mindset. Which lies at the base of many things. It was a good intro book on the power of perception, narratives and perspectives/mental filters.
The 4 hour work week by Tim Ferris changed my.perception what work could be and how I could design a life around meaningful and fulfilling work.
Those books I listened to on my Ipod while walking in a nearby park. For a full year every morning I got up, put on my audiobooks and started walking. The benefit rippled into the future. It's funny that on those walks I often couldn't envision a life worthy of my being. I wasn't pessimistic as much as I just didn't get how all the info and exercises from the books would bring a better life into being. And here we are. The latent and potent power of books is unimaginable. Provided you perform the required actions to match said information.