I am surprised you didn't mention sitting on the floor and/or sleeping on very low mattresses.

Getting up and down from the floor takes every muscle in the body. Try it!

If you aren't in shape, go camping for a few days and sleep and sit on the ground. See how your body feels after just a day or two of it.

Lots of Americans walk--especially in cities. But almost none of them get up and down from the ground dozen times a day.