That would be easy - I would finally kick myself into finishing all my fanfics, which are in progress and deleted those I wouldn't be able to finish, because why to leave your readers hanging?
Then I would write letters to people who meant something to me, to tell them what they meant to me. It would be unlikely I would be able to tell them myself so why not to use the paper?
And last but not least, I would get a good drink, got some pretty haircut and makeup and clothes - because if I'm going to die, I can at least look good.
It sounds as if I'm making fun of people - but really, I would do all of this.