Digestion is quickly shut down during stress…The parasympathetic nervous system, perfect for all that calm, vegetative physiology, normally mediates the actions of digestion. Along comes stress: turn off parasympathetic, turn on the sympathetic, and forget about digestion.

We live well enough to have the luxury to get ourselves sick with purely social, psychological stress.

Most people who do a lot of exercise, particularly in the form of competitive athletics, have unneurotic, extraverted, optimistic personalities to begin with. (Marathon runners are exceptions to this.)

Finish this lecture, go outside, and unexpectedly get gored by an elephant, and you are going to secrete glucocorticoids. There's no way out of it. You cannot psychologically reframe your experience and decide you did not like the shirt, here's an excuse to throw it out - that sort of thing.

But often, it's easier to resist temptation with distraction, or to be so inculcated in doing the right thing that it's automatic, outside the frontal cortex's portfolio - Then it isn't the harder thing, it's the only thing you can do.

What does the frontal cortex do? Gratification postponement, executive function, long-term planning, and impulse control. Basically, it makes you do the harder thing.

It's probably even the case that if you stoked up some Buddhist monks with tons of testosterone, they'd become wildly competitive as to who can do the most acts of random kindness.