I’m 60 and I like to do about four and a half miles on the elliptical in a half hour. (Low impact). If you do it regularly, it’s not at all tiring. I imagine, gee, all have to do is repeat this seven times and I’ve done a 3:00 marathon.
Nope.
BTW, I remember my 25 mile march on the last week of basic. I was ok, but it took a lot more than three hours.
Broke my back.... Just damn sore to run but I get in about 5 miles a day walking. Walk before and after work as well as my morning an afternoon breaks. No more running. Have to stand an fight now....:o)
Or try...
Stay Safe....