I just finished reading the The Monk and the Riddle. The following quote sums up the book, and is about all you need to know (or read) about it. The rest was just fluff.
Work hard, work passionately, but apply your most precious asset – time – to what is most meaningful to you. What are you willing to do for the rest of your life? does not mean, literally, what will you do for the rest of your life? That question would be absurd, given the inevitability of change. No, what the question really asks is, if your life were to end suddenly and unexpectedly tomorrow, would you be able to say you’ve been doing what you truly care about today? What would you be willing to do for the rest of your life? What would it take to do it right now?
The Monk and the Riddle, pg. 156