Do you have hopes or plans for the future that might not end up coming true if you don't get off your duff? Do you have a message you want to pass onto your older (more mature?) self? Consider sending a message to yourself through www.futureme.org.
Now, granted, there's no guarantee the message will actually GET to you in the future....so you might want to consider keeping that "1000 things to do before I die" list handy as well.