We know that taking cold showers that are too cold is a bad idea that leaves you worse off than taking warm showers.
We do?
I've always interpreted the idea of cold showers (in this context) as brief but intensely cold, preferably preceded or followed by hot showers. It's the same idea as running out of a sauna, rolling in the snow, then running back in (highly recommended, by the way).
I thought I had come across an article on this on Getting Stronger, but I'm having difficulty finding it at present. The main thing I'm seeing now is this comment:
The key here is adaptation: It’s dangerous and silly to expose yourself to water or air temperatures beyond your adaptive range.
To the fun theory, hedonic treadmill sequences.
http://gettingstronger.org/hormesis/
TL;DR stoicism with science.
Key idea: OPT, Opponent Process Theory: http://gettingstronger.org/2010/05/opponent-process-theory/
Research, PDF: http://gettingstronger.org/wp-content/uploads/2010/04/Solomon-Opponent-Process-1980.pdf
From the article:
"In hedonic reversal, a stimulus that initially causes a pleasant or unpleasant response does not just dissipate or fade away, as Irvine describes, but rather the initial feeling leads to an opposite secondary emotion or sensation. Remarkably, the secondary reaction is often deeper or longer lasting than the initial reaction. And what is more, when the stimulus is repeated many times, the initial response becomes weaker and the secondary response becomes stronger and lasts longer."