Books: Philosopher of Optimism

This article - Philosopher of Optimism Endures Negative Deluge - from today's NY Times reminds me being positive and optimistic is a habit I can adopt and practice.
Quoting from the article:
That foundation, he said, is that human perception is intentional; the pessimists themselves paint their world black.Mr. Wilson has spent much of his life researching how to achieve those moments of well-being that bring insight, what the American psychologist Abraham Maslow called "peak experiences."Those moments can come only through effort, concentration or focus, and refusing to lose one's vital energies through pessimism."What it means basically is that you're able to focus until you suddenly experience that sense that everything is good," Mr. Wilson said. "We go around leaking energy in the same way that someone who has slashed their wrists would go around leaking blood."Once you can actually get over that and recognize that this is not necessary, suddenly you begin to see the possibility of achieving a state of mind, a kind of steady focus, which means that you see things as extremely good."