One of my favorite things is to sauna, then cold shower, then brief sauna again, and my nerves get totally reset such that I can go sit in a -20C chair outside

One of my favorite things is to sauna, then cold shower, then brief sauna again, and my nerves get totally reset such that I can go sit in a -20C chair outside and will not be cold for a surprisingly long time. It feels great. If the water is not cold enough, it is disappointing.