Jason Shen said that voluntarily taking cold showers increased his discipline. Can you imagine a different experience if you chose cold showers instead of being forced to take them?

I don't feel like I've properly had a shower unless the shower has raised my core temperature, but I'm going to give this a try. The easiest life hacks are ones that don't require a time commitment and only minor changes in routine.

Taking a cold shower lowers your body temperature, then your hypothalamus kicks in to compensate. You get out of your cold shower, and your body heats up. If you take a warm shower, you end up cooling down after the shower.

Not my experience. Sometimes I take a cold bath (ice is involved) after running. With enough ice, I feel quite cold for many hours after getting out -- to the point where I get out an extra down comforter to sleep with, and am still cold.

That means you have lowered your core temperature and your body is simply unable to respond to that coldness quickly. It's vital that you feel cold at that point. Quick cold showers are just "tricking" your body.

I have taken cold shower almost all my life. Initially because my home was not equipped with a hot shower and later as an exercise is self control when shower became available. It may have felt better if you either adopted to it or it was not forced in the first place. One benefit which I have experienced is that outside temperature feel less harsh once you come out of the shower.

I've noticed this, too. Once I step out of the shower and dry off, I actually feel unusually warm, perhaps because the cold water forced my body's internal heating mechanisms to start working harder.

Precisely. I was raised on 'Kneipp Kur' showers and I still do it every day. The thing is, its a lot more effective, if you taking changing temperatures. Hence, I shower hot first to get clean and then cold at the end. Makes you feel awake and also you won't freeze when you get out of the shower ;-)