The calm in the eye of the storm

I've experienced what is described in terms of Andy's reactions, in the quote below.  When after several months of torture, I finally 'clicked' that what was happening in the workplace had been deliberate and intentional abuse, something switched in my head.

My focus became much sharper, my intentions ruthless

And suddenly I became calm.

The Psychopath Makeover - The Chronicle Review - The Chronicle of Higher Education

[In the lab, our pulse rates are significantly higher than our normal resting levels, in anticipation of what's to come.
But with the change of scene, an override switch flips somewhere in Andy's brain. And the ice-cold Special Forces soldier suddenly swings into action. As vivid, florid images of dismemberment, mutilation, torture, and execution flash up on the screen in front of us (so vivid, in fact, that Andy later confesses to actually being able to "smell" the blood: a "kind of sickly-sweet smell that you never, ever forget"), accompanied not by the ambient spa music of before but by blaring sirens and hissing white noise, his physiological readings start slipping into reverse. His pulse rate begins to slow. His GSR begins to drop, his EEG to quickly and dramatically attenuate. In fact, by the time the show is over, all three of Andy's physiological output measures are pooling below his baseline.
Nick has seen nothing like it. "It's almost as if he was gearing himself up for the challenge," he says. "And then, when the challenge eventually presented itself, his brain suddenly responded by injecting liquid nitrogen into his veins. Suddenly implemented a blanket neural cull of all surplus feral emotion. Suddenly locked down into a hypnotically deep code red of extreme and ruthless focus."

Despite the title of the article, there is no sense in which I am psychopathic, which is why, when I originally had my strange change of mental gears, I thought this ability to throw care to the winds and focus on extricating oneself effectively from a very bad situation must have been part of everybody's brains.

The writer's discussion implies that this isn't so, however it is likely that one would have to be put through a very prolonged, grueling experience, first, in order for the brain to ultimately resort to this extreme mode of adaptation.  Sitting in a lab doesn't cut it.

I do empathize with people deeply, under normal circumstances.  However, having been to this extreme point and back, I know that should somebody physically attack me, I would not require the build-up of months of provocation, in order for to move into the zone where I could adequately defend myself.

I'm capable of entering the eye of the storm because I've been there before. I also know that my mind calms down and that I am supremely confident in doing what has to be done to prioritize my own survival.