"Why greatness cannot be planned". Changed the way I search for new ideas. Instead of goal setting and conquer-and-divide approach, I allow myself to be guided by what I find interesting, even if it seems to be wasting time. In the book, the author calls that "finding stepping stones". I always felt that this is a better way to create new things but was unable to put it into words.
There's also a talk: https://www.youtube.com/watch?v=dXQPL9Gooy