I'm not talking necessarily about flying. But taking a train/bus/car is all tiring. Why?
We're sitting, not standing. If we aren't driving we don't have to pay any attention to the road. It should technically be comfortable. We are moving, but many times cannot feel it (trains and planes are usually pretty smooth).
Is it somewhat psychological, physically moving from one place to another, that hasn't gotten easier over centuries?
Is it because there is some magical about going from one place to another (not psychological but real) that makes it exhausting?