I somehow stumbled across this article about how happiness correlates with age, and I enjoyed it thoroughly. You should check it out. Money graf:
"In a study published in September in Psychological Science, Wood and her collaborator, neuroscientist Michael Kisley of the University of Colorado, recorded the brain activity of 63 adults, ranging in age, who were shown a series of negative and positive images, such as dead animals or a bowl of ice cream. Older adults were about 30% less reactive to the negative images compared with the younger adults."
Anyway, I figured that I could attempt to replicate this article's findings in my own life. I'm sending the article to myself using a 13-year time delay (I'll be 32!), reading it again, and deciding whether or not I agree with the results then.
Two key assumptions: 1) that I'll still have the same e-mail address and 2) that I'll still be alive. But as long as those two points are met, we could be in for some pretty sweet results. Bookmark this page, and come back in 2020.
Edit: By the way, the program I used to send myself the message in the future was called Time Cave. I've never seen a website with more incentive for people to donate.