Why train hard if all we want is to enjoy

Imagine two people walking up a mountain on a bright sunny day.

One is a seasoned mountaineer, skilled both in endurance and in surefootedness.
The other has never walked on a mountain, is very much on the limits of his endurance plus he is not used to the height.

Who can enjoy more? I think the first one, because he has plenty of power left to appreciate the sun, the view, the fresh breeze,… The other one probably has to look at his feet most of the time while gasping for air.

The point I want to make is, that hard training (not so hard as to produce trauma but hard enough to make you tougher) increases the number of situations which you can enjoy in your comfort zone.
If the situations get tougher, it also (and this is important for survival) vastly increases the number of situations you experience as “adventure” instead of “life threatening”.

So why not just train hard?