There's an ongoing joke in my family that I'm sure I've mentioned before, along the lines that we're sure my dad won't ever retire because he doesn't know HOW to retire. Unsure what he would do with himself in retirement besides watching television, sleeping, and being yelled at by someone (likely his daughter), and rather than thinking about it too hard, he chooses to keep working.
Unlike my dad who won't retire, I'd be happy to retire, though not in the traditional "let's learn how to golf and square dance" sort of way. Instead, I'd likely keep working while in my retirement. My working would be more like "working" than working: building the things I want to see exist in the world, instead of building things to make other people money. I would (will?) have a giant list of things to build, and a sense of "oh, shit, I have only another 60 years left in this life" urgency to finish them all. That would get my butt in gear.