Being a clueless weekender, I don't count the miles very much. I figure that if I ever were to advance beyond "clueless weekender" it would take a long time to get my trail legs at my age.
Once, 30+ years ago, I did 50 miles in a 3-day weekend. I could hardly move for about three weeks afterward. Yeah, I know, you have to work up to it, but my buddies were going.