"What is the book that changed your life? (not novels or religious texts)"
I think it's a wonderful way to connect in a less superficial way and learn a little more about each other. It's also a wonderful way to discover new books worth reading.
This is one of them:
The Road Less Traveled: A New Psychology of Love, Traditional Values, and Spiritual Growth
M. Scott Peck
A psychiatrist suggests ways in which confronting and resolving problems, a painful process most people try to avoid, can lead to greater self-understanding and spiritual growth.