I work in a rural area for a Fortune 100 electric utility. We have had several high performing people break down at work; one was away for a year and was a shrunken shadow when he returned, barely able to hold a conversation. Two years after returning he is mostly recovered. Stress is no joke.
I would have said I have no anxiety problem either, but one day I was trying to get paperwork done while the usual whirlwind was going around me, and I nearly blacked out; when I came around I had a lump in my chest. It was diagnosed as an anxiety attack, which often triggers esophageal spasm.
Stress is central to several maladies today – cardio-vascular disease, immune problems, and possibly some cancers. Humans have rarely had problems with predators, even in the fossil record chewed human bones are rare. We have a much more voracious foe now.