From Helpguide.org:

Chronic stress wears you down day after day and year after year, with no visible escape. Under sustained or severe stress, even the most well-adjusted person loses the ability to adapt.

Please note the use of the phrase “even the most well-adjusted person”.

It’s not any one thing, you see. You could go down the list of complaints and issues and pick each one off, one by one. Except that when you get to the end of the list and you rub your hands together in satisfaction at having addressed the problem, what I am left with is a mountain of small changes. A mountain. And after all of those changes are said and done, we are still here. And for what. For what?

It’s not any one thing. It’s all of them. Day after day after day.