10 miles walking would be about 2.5 hours to 3.5 hours if relatively flat and paved. All bets off in technical mountain terrain, or at altitude.
I realised that I led a sedentary life after being invited by colleagues to do the Great Cautley Challenge
At the time it was said to be 30 miles long and they did prepare me with some shorter walks, maybe to check I was up to it. Oh, and the catch was it had to be done in under 10 hours. As a student, I'd done the Three Peaks walk, but there was no time limit other than the hours of daylight.
For the greater part of the challenge I was doing fine, but ISTR the last stage was one of the hardest and I was really struggling, part-fatigue and partly a blister I had developed. I just managed it, struggling in at 9hours 57minutes. During the walk we were passed by several fell-runners who were running the route
My colleagues, one of whom was a 6'3" former coal miner, found it relatively easy. He was a pretty good cyclist too.