Already have all the necessary legal items in place. But what I do with the culmination of the thoughts is allow it to help me plan my future. For example, I decided to retire early instead of continuing to chase money, we have to live closer to the bone, but time is precious so we (my wife is retiring in a couple of months) decided we’d rather spend it together rather than keep waiting and hope we have time later.
And a few decades before that, John D. MacDonald (best known for his Travis McGee novels) wrote The Girl, the Gold Watch, and Everything.
I’m 63, and in the past year or so, I’ve been thinking both backward and forward in time differently than I used to.
Backwards, it’s started to really hit me about the sweep of time I’ve lived through, the changes I’ve seen. And especially about how, regardless of how crappy things seem at any given moment, the world is really a much better place for most people than it was 55 years ago, when I first started to think of the larger world.
Forward, I’m aware that while I still have a lot of time left in all likelihood (my father died at age 90, and my mother is 90 now), it no longer stretches out ahead seemingly infinitely. If there’s stuff I want to do, I’ve started to realize, I’d better get on with it. If I want to go to Montana a few more times, if I want to go to Greece, if I want to go to Alaska, I’ve got maybe two decades at the outside where I’ll not only be alive to see these places, but be able to be a mountain goat on hiking trails when I get there.
And I’ve been thinking about the time when my body (“Lord, my body has been a good friend” - Cat Stevens) gets to the point in its decline when I will have to trade a two-story-and-basement house with a yard and woods in the back, for something that doesn’t require much maintenance, and involves less of the up-and-down that doesn’t faze me now. But I will stay active, and push that time back as long as I can. So far, so good. 
When I was a child I imagined what I would do if there were a velociraptor attack. Later, less whimsically, I replaced dinosaurs with spree shooters. Now I’ll think of a raptor with a gun.
Sometimes I imagine the world like a video game map editor, then wonder what would happen if you took all the, I don’t know, ducks and put them in a big pile. It’d be chaos.
My imp of the perverse is healthy. I often think how easy it is to ruin your life. Like if you see a cop you could scream “fuck you, pig” and tackle him. Or when driving down the road you could move the steering wheel just enough to hit oncoming traffic. A couple degrees, at most.
When I imagine how interconnected the world’s industrial output is I tend to think how it goes backward in time, but my knowledge of this isn’t good enough to come to any conclusions. Most things are made in factories, which are made with machine tools, which were themselves made with other machine tools in a factory somewhere. So one could construct an evolutionary tree of machine tools going back how far? Does it actually go back to some hominid ancestor banging rocks together, or is there a discontinuity somewhere? Whenever I see one of those “this is how they make a million widgets in a day” specials I want to see how the widget maker is made. It’s widget-maker makers all the way down.
Like others here I have the experience of trying to imagine what everyone in the world is doing and holding it in my head, like how many African nomads are milking goats, how many people are stuck in traffic, or constructing insane scenarios that could happen due to the rule of large numbers.
The Tetris effect occurs to me for certain games. Years ago when I played the Mario Galaxy games I’d imagine how a small Mario would navigate environments to get a star placed on a high location, especially looking for clever wall jump potentials. Or using a portal gun for maximum efficiency.
I am completely weirded out by books. You’re reading a book, and there’s this entire universe full of stuff and people and things going on, and then you go and get a glass of water and come back to a smallish hunk of dead tree with some ink smeared on it. Where did that whole world go…?
More generally, how does a couple of pounds of fatty meat have room for not just our actual world, but reams of additional unreal worlds full of stuff?
I also have a major thing for fictional plants that produce non-planty stuff; when I was a kid I was all over the candy-producing plants in the Raggedy Ann stories, the lunchbox and dinnerpail trees in Oz, and all the punny plants in the Xanth series until it got too boring/skeevy, and there was a great manga series, Silver Diamond, with many excellent magic plants in it that I was greatly enjoying until the publisher went kaput. I have several self-designed daydream worlds each containing different varieties of magic plants for whiling away the occasional half-hour. I have no explanation for this.
I often think about places I could stay if I were ever homeless. I’ve never been close to homelessness, nor have I personally known someone that was homeless, but the idea sticks in my mind.
If I’m ever downtown or around some camping areas, I sometimes make mental notes of good shelter, and how I could avoid being kicked out. Certainly not every time I go out, but I find a new spot every few months or so. The list is reasonably long now.
For all those pondering the interconnectedness of the world, and all of the people involved in every little thing, webcomic author Howard Tayler had a relevant blog post a couple of Thanksgivings ago.
marshmallow, I also think about the continual bootstrapping of technology sometimes, but I do know how to make a few zeroth- and first-order tools (that is to say, tools you can make with no other tools at all, and tools you can make with those tools), as well as some of the big jumps between there and modern tech (like how to measure distances in nanometers, using a ruler marked in millimeters). If anything, knowing those things makes the whole process more wondrous, not less.
I think about how even the most mundane, everyday things become unbelievably weird from an alien perspective. Imagine an alien anthropologist:
The creature emerges from its period of torpor. It appeared to be running crude simulations of its world while in this state, though the overall purpose is unknown. The creature then enters a chamber that sprays a chemical solvent sourced from a central reservoir. It uses other chemicals to clean numerous protein cylinders extruded from the creature’s surface. The solvent needs to be in a precisely calibrated temperature range; a mere 1% variation was enough to cause the creature to emit a sharp acoustic burst consistent with past indications of distress. We were initially confused that the amount of solvent drained from the chamber was greater that entering, accounting for evaporation–a high concentration of nitrogen compounds led us to realize the difference was emitted by the creature.
And so on. But what really gets me is the realization that my “alien” is barely more alien than the rubber-masked guys in Star Trek; I mean, it exists in three dimensions, understands what chemicals are, has a sense of time, etc. I can’t really imagine what an alien is like, or even get remotely close.
I’ll sometimes think about explaining how some technology works to someone from the past. In a way that’s about explaining the most important things that exist and why they aren’t magic.
Sometimes, like with computers, it’s a version where you explain why the predicted stuff didn’t happen, and what actually did. I think it started because of watching Bewitched, oddly enough, when they would accidentally pull up someone from the past.
That was brilliant!
Like some others who have posted here, I often think about how a person from the past, say the Roman Empire, would react to modern technology. I think he could imagine that cars were powered by small animals under the hood, but planes and phones would simple be magic.
Also, I imagine what would happen to human artifacts if all the people vanished. Plants would cover a lot of stuff pretty quickly, especially in the tropics. Eventually water would get into high rise buildings and they would collapse.
Stephen King defined writing as “telepathy.” I think of it as “magic.”
When you read Shakespeare, you are reading something that was in Shakespeare’s thoughts. That is so wild.
I’ve seen this start to happen in my old bedroom. An enterprising houseplant had managed to grow a tendril up to and through a chink in the windowframe. If we hadn’t pulled it out and nailed that board a bit tighter shut, it’d have eventually pried it off.
This will surprise not a single person, but occasionally I fantasize about living underwater with sea creatures.
The thing about this thread is that there’s rarely a weird thought I have that I don’t eventually share, for the sheer amusement of seeing how my loved ones react.
The most recent was using a mole-based pen name for my novels (my last name can have the word ‘‘mole’’ inserted into it and only slightly change the actual name), and my erotic novel pen name would be some spin on Naked Mole-Rat, with a sexy librarian mole on the back cover.
That was a real thing that passed through my mind, so I was delighted to share it with my husband just to see the look on his face. His response was something like, ‘‘Or… and I’m just spitballing here… we could do none of those things and never speak of it again.’’
Often, when I disturb an ants’ nest while gardening, I put on a high pitched voice and squeak stuff like “The Eye! The Great Eye! The legends were right! We should never have abandoned the old ways!”
Next time for sure. 
When I go for walks in town I like to imagine what’s happening inside each of the houses. I look at the yards as I go by, and make up little stories to myself of what might be happening inside each house based on what I see in the yard. I usually end up going past one of the older houses in town with peeling paint and shingles coming off, overgrown weedy yard and crumbled sidewalks, and I imagine dark and interesting scientific experiments going on or something like that. Makes the walk entertaining.