Experience the Holy Spirit & live in the world
This book offers a practical and spiritual approach to experiencing the Holy Spirit and contact with God.
Thomas Kelly is a Quaker and explains both motivation, methods and results for experiencing God. It is not a "self-help" book, but a spiritual one.
At times I felt I could not reach the perfection he seemed to talk about, but he explains that this is a process, and not always directly progressive. After reading the book I realize that you can keep in almost constant contact with the Holy Spirit, God, but do not have to become a mystic isolated from the world.
You do not have to be a Quaker or a Christian to get a lot of insight from this book.