So I just measured my between class walk routine, and it comes out to 1.8 miles (probably a bit more because I wasn't very detailed with the path). Doing that three times a week isn't that much, even for me, but it's what I have time for. What I suddenly realized though is that it's a big step up from 5 years ago at the end of high school when my tendons hurt after just 1/16 of a mile, as compared to not even really feeling the burn at all now. I've always wagered I'd been making some progress, but never actually measured it by any objective standard until now.
(For context, 11 years ago I had major surgery on both legs because of tendon issues which makes it hard to walk long distance and some other things. It isn't general "being out of shape" or anything.)