1000 steps takes about 10 minutes.

15K steps takes about 150 minutes.

150 min by 52 weeks in a year is 130 hours a year.

130 hours a year from say age 30 to age 80 is 6500 hours walking.

And so that gains you 3 years, which is 26280 hours, or 17520 awake hours.

So you are gaining about 17520-6500=11020 hours of life to use for things other than walking which is more like just under 2 years in days counting only awake hours.

Now of course it's certainly possible to do things you enjoy while you walk or perhaps things you would have done otherwise while not walking.

For instance I suppose a treadmill desk and using it to walk when you would have just been sitting instead.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9628515/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9637007/

https://www.frontiersin.org/articles/10.3389/fpsyg.2021.6694...

I think it's tempting to ascribe some lost ancestral knowledge to older house, but to be completely honnest a lot of them weren't designed with thermal considerations in mind (or rather, the thermal efficiency was accidently achieved by following some heuristics).

A lot of these older houses were simply badly insulated. They required a lot of wood or coal to keep warm during the winter or had the occupants wearing layers inside at all times but would cool down quite fast in the summer during the night, only to heat up again during the day.

Good, explicit thermal design appeared with mid-century houses. [0]

[0] https://www.youtube.com/watch?v=Qq-3cZ0cbws

Waittasec. That happens?