Along with some friends, I'm currently reading Authentic Happiness by Martin Seligman. Upon looking at the jacket after it arrived from Amazon, my first thought was that I've finally become my parents. My mom was about this age when she started reading self-help books. That's how it's marketed, but before I was through the preface, I could see that this was no self-help book. Those books are about subtracting negatives from your life. This one is about adding positives.
In the book's first sentences, Seligman lays the groundwork: "For the last half century psychology has been consumed with a single topic only - mental illness - and has done fairly well with it. [...] But this progress has come at a high cost. Relieving the states that make life miserable, it seems, has made building the states that make life worth living less of a priority." This book is about positive psychology: the study of positive emotions, traits, and institutions.
I say it's about time. The world needs this. If you never stop thinking about broken things - even with the good intentions of fixing them - then all you ever see is broken things, and that's depressing. Eventually you'll lose your motivation to keep fixing.
One way this shows up is in the difference between "win-lose" situations and "win-win" ones. A win-lose game is a competition: you date the hot girl and somebody else doesn't. You get the promotion but not your coworker. Some situations are competitive by nature, but not all are. Sharing your enthusiasm is win-win because you energize the people around you. Helping somebody move into a new house gets the job done and makes you better friends. OK, fine. But the key thing to realize here is that you can choose what to focus your attention on. If you focus on dating the hot new girl, and helping your friend move takes a back seat, you've just chosen to turn somebody into a loser instead of helping someone.
To take it a step further, not only can you choose between win-lose and win-win situations you're presented with, you can actually create win-win situations. Start a how-to site on the web. Run a meetup group to bring together passionate amateurs. Make the world a better place, and you can't help but win.