Well I don't know if this book really improved my life overall, or any of the other criteria you mentioned, but it definitely had a HUGE impact of my life...

"The Little Prince" is such a beautiful, touching book with a ton of hidden meanings. It's just really deep. It seems sort of like a different type of love story, but it's also very sad, observant, and deals with a darker side of life. I don't know, but somehow that book just really strikes a chord in me.