Forcing oneself to stay in a cold shower demonstrates the prefrontal cortex's ability to act as a brake on other brain centers.

“A really good example, it's kind of a trivial one in the context of today's discussion, but it's a concrete one so I'll use it, it would be, I know many people out there use cold showers as a way to stimulate metabolism and build up resilience and this sort of thing. If you get into a very cold shower and you feel as if you want to get out, but you force yourself to stay in, you're forcing yourself to stay”