Little knowing this, I just tried to walk to the other end of town and back. Just a light walk, which I used to do all the time. 10 km, or about 6 miles, if I'm remembering correctly. I managed the walk. And now most of the muscles in my body seem to be on fire. *curls up in a ball and concentrates on breathing* gahhhhhhhhhhh.
BUT, to take my mind off the pain, I invented all kinds of technical specifications for my world. Inventing a world is terribly jolly. If you want vacuum sealed trains in your spaceship, in go vacuum sealed high speed trains. In you want medical robots with centipede legs which live under the floor, they are there. With pin stripes. If you want- but that would give away more of my story than I care to give away right now.
Suffice it to say that it was a fun walk.