I found a little article called How to Be an Incurable Optimist over on eHow. Here's part of what it says:
One way to become more optimistic is to meditate. Recently I was in a Women's Spirituality Group. No matter what topic we chose we always ended up talking about "Living In the Moment". That seems to be the main message that buddhist traditions teach and the purpose of meditation. According to Eckhart Tolle, you can't be unhappy if you are truly living in the moment.I'm certainly not going to disagree with that!