THIS is the orginal: if you are seeking a refined, self-guided, well-written-to-provoke-you aid to help you define your 'reason for being', this is the best I've seen. I have bought it for several friends, and have suggested it to therapy clients. All because, 10 years ago, I found it and used it for myself. I remain grateful.
This book is well done, quite pleasant in its writing. The three authors, brothers Linn and the wife of one, share their voices throughout. You don't feel like you are merely reading, but being involved in a thoughtful conversation.
At the end of each section/chapter, there are steps to do to consider and integrate the conversations into your own thought process. I recommend you consider getting a note book to jot down your responses. Or write in the book and keep it private. (I have my own private copy, and always keep another un-touched for others to peruse when I tell them about it.)
I also enjoy this for group work. I have used it once it its entirety (their is a section on how to do this at the end of the book). But it is also excellent for starting conversations about what matters most to you, helping yourself or others discover roadblocks to becoming, getting past times of discouragement and becoming okay with a joyful, successful life.