The typical "western" approach to happiness is: "I have X but I want Y, therefore, to be happy I need to achieve Y." This book reverses the equation: "I have X but want Y, therefore, to be happy I need to learn to want X." That idea may sound radically counterintuitive on first hearing, but it's reflected in many of the world's spiritual traditions.
What's especially great about it is that it approaches the subject from a rational, scientific viewpoint, so if you find yourself turned off by the spiritual side of buddhism or whatnot, the book will be welcome.
Also, music is a good call generally - the ability to play an instrument will repay itself many times over a lifetime.