I'm currently halfway through reading The Great Divide by Stephen Pern (1987), a walk along the Continental Divide of the United States, in which he appears to walk at a collossal speed most of the time, the exceptions being when he was slowed down by snow or bad terrain, covering 30 miles or more day after day.
By comparison, my walking speed is what you'd expect of someone the wrong side of seventy
.
Personally I think the fact that I'm still walking at all, compared to many people in the same age group (or lower!) speaks volumes about my health!