John Piper's Desiring God was probably one of the most influential books in my life, if not the most influential. Since reading it, I have consumed several other Piper books, the most recent being Future Grace (1995).
At its base, this is a book about sanctification, but not sanctification in our own power. Rather, Piper camps on God's promises and particularly His promise to be gracious to us, not only in the past but also in the future.
Piper intentionally built this book around 31 chapters so that it could be read over a period of a month. I began that way, but found it difficult going. When I sped up and read it as it came, I found a much deeper appreciation for the book. Piper applies his notion of future grace to a wide variety of issues in the Christian life. However, his chapters on despondency, lust, and suffering were the finest chapters in my opinion. It seems to me that Piper's writings on suffering should be required reading for the Christian (watch the video below for an idea). His chapter on suffering from Desiring God knocked me off my feet. This one was nearly as strong.
The only real drawback that I see was that this book is a tad repetitive. Though I suspect Piper was intentionally repetitive around the theme of future grace, as the central thesis of the book, it sometimes came across as redundant. I am not entirely sure why I felt that way, but I did.
Future Grace is a good book for someone wanting to understand the role of grace in the process of change and sanctification.