I ran cross country in high school, and we regularly would run 10 miles, and then college happened and I had knee surgery... Now I could probably get in half a mile.
13.1 miles (half Marathon) this last April 9 months after my second ankle reconstruction and 3 weeks after my 40th. Another half in Nov and a full next April.
20km with a 35 lb pack and rifle for a post wide competition. I just Googled it and its a fuzz under 12.5 miles.
It was a "Run, Blast, and Shoot" competition. Your squad ran one leg and got to station #1. Everyone drew a weapon name out of a hat, sat in front of that weapon, field stripped it, reassembled it, function checked it, and once the last guy was done your squad could continue on. At Station #2 you drew a land mine name out of a hat, armed it, then made it safe. (Except the guy who drew the Claymore, he actually set his off). Ran to Station #3 which was the rifle range, dropped straight into a fox hole and fired 40 rounds. Misses counted against your time.
My squad finished 2nd. We weren't the fastest, but we shot very well which pulled our score up.
Ran a 3 mile race then ran (jogged) home with a world class tri-athlete for a 11.5 total once. Learned more on that run than any other. It was crawling for him. He just poured the info over me while keeping me going. If I ONLY ran my body (joints) would revolt, if my training also involved swimming and biking I seemed to do OK.
How far I can run depends on how many steps it takes the person chasing me with a knife to bring me down. It won't be many. I can make it to the mailbox when I'm feelin' extra sporty, though.
We would do 8 mile battalion run every other Friday. 25 miles road marches was always way worse for me than any run. I was usually humping a 23lbs m60..it sucked