The case for the mountains
The beach sells relaxation; the mountains sell perspective.
At altitude the air thins, the noise falls away, and the scale of a ridgeline does something a flat horizon never can: it makes you small in a way that is oddly restorative. A trail gives you a goal with a summit at the end of it, and the reward is earned rather than handed over with a beach chair.
You come back from the coast rested. You come back from the mountains changed.