Start blogging. Maxine at Petrona links to findings that blogging raises the spirits -- and to some other things as well.
I liked this:
Lastminuteliving.com, which commissioned the study, managed to drop in the fact that they have a lot of bloggers: "Creating a blog can be a way to get more out of your life. Judging by the amount of users we have, people like sharing their photos, videos and personal thoughts with others."