As I’m really fond of the comparison. Your daily activity level, which you sustain more or less everyday and have been for years is something some people set out to do as a time-fixed gargantuan journey and many do not even finish. They have a deadline at which point they seize and return to normal activity levels. You’ve maintained this activity level for far longer than they do.
Take anyone of these people mid-way through their hike and ask them to go for a run, what do you imagine their reply would be?