I did a 20 mile walk for charity when I was a teenager... no way I could do that now.
There’s a lot of things I could do then that I can’t do now, like the 15 mile hikes we did in the Scouts, for example.
Eek! Yeah, that’s a long way!
I work with a gal who *walks* marathons on a regular basis, and who often walks twenty or thirty miles just for the heck of it. For me, them are biking distances. ;-)