What's the best book about focus, concentration and flow that you can recommend?
Second person to recommend me this book. Must be good.
Very very good. I actually need to get on reading it again soon, or at least reviewing my notes on it.
A good companion to the book above, The Five Elements of Effective Thinking: https://www.amazon.com/5-Elements-Effective-Thinking/dp/0691156662
Big ups for this one. It covers so much in practice and theory. Very re-readable, as others have said.