[munificent]

"Should" is a moral of value judgement but you provide no argument for it.

You could just as easily say: "People aren't pushing themselves anywhere close to their limits. If you look at the extremely obese who eat jars of mayo in one sitting or consume tens of thousands of calories a day it's evident that human limits are far higher than what the average person is willing to endure. For the average person they should probably be eating way more."

What is so intrinsically good about reaching one's limits?

[tachyonbeam]

It's also true that young gymnasts retire in their mid-to-late twenties. They get injured a lot. I'm not sure what they get for their efforts, besides medals and prestige.

There's definitely value in getting out of your comfort zone, but that doesn't have to be hard. IMO it's only worth pushing yourself hard if you really believe in something. Don't do it just because others are pressuring you to do so. Rest when you need it.