All those things are hyperbole, repeated endlessly to warn people away from exercise. It's a cultural thing, and we're embedded in that culture. But exercise is the normal state for humans, and to think otherwise is a weird local phenomenon.

The mirage of 'an improved diet' is the current fad idea and the topic of this conversation. Why doesn't it work for most people? Why are there 1000 books about it, and still no consensus?