This book is a great read for those in their twenties who feel lost and depressed and don't know why. Jay stomps the notion the popular notion that your twenties don't matter and that life starts in your thirties, and explains the ways in which our generation need to start taking charge of our lives. Without being too self-helpy or academic, "The Defining Decade" was able to provide sound psychological advice on problems twenty somethings face, and it has definitely given me (a 23 year old) insight on certain things I never thought about before.