Ninjas. I'm going to be killed by ninjas.
When I'm old and I've done all the things I want to do or there's no chance I'll do any of the things I haven't done, I'll contract assassins to hunt me down. It can be any time, any place, just as long as I don't know when and where. The only rule is that they need to be many, and it must be with swords.
And I'll carry a katana with me for the remainder of my days, because I'm sure as hell not going down without a fight. I might have hired them myself, but they won't know that, and I'll be damned if I'm not determined to take a few of the bastards out with me.