Eckhart Tolle's books The Power of Now and A New Earth have been really life-changing. His ideas are similar to others' in that there's some discussion of mindfulness. However, sometimes the message just needs the right messenger.
I recommend listening to his books on CD/iPod instead of reading them. He has a calm, sensical voice with a touch of underlying humor.
At least temporarily, he's replaced all music on my iPod, as I wear the headphones to putter around the house and garden.
Regardless of your religious persuasion (all points on the belief spectrum and cultural backgrounds), the message is quite reasonable, practical, and positive. My day is better, and I haven't given up anything (except the negative). My wife dogged me for a while, asking me what I'd done that made me so different, in a good way.