That's one of those things that might sound nice, but it IS possible to push one's self too hard. And too hard is just that: Too hard. An eighty hour work week (as an extreme example) might be sustainable for .5% of the population, but for every other person it will exact a toll more significant than the benefits. But you're right in that preparing for occupational stresses and hazards should be seen as an inevitability and planned for. Lots of people wait until it hits them (or well after that point) to do something about it.