[notacoward]

> why is the tendency to increase the distance

Up to a point, because most of the sought-after benefits do scale with duration (for which distance is a proxy). But that point is pretty quickly reached. A few 5km runs a week at moderate pace is plenty. I run a bit more than that, and I do notice a difference, but I'm well aware that the returns are diminishing. Beyond that, I think it's largely about pride of accomplishment, or about ego, or maybe those are just two sides of the same coin.

Either way, it's important that motivation matters. To many people it matters far more than improving performance. Increasing pace by even a few percent is really hard. Running 10% further is pretty straightforward, as is training for something even longer. Those are easy goals to set an measure against. If that keeps people going then it's a good thing, even if it's also true that they should try to minimize the negative impacts (heh).