After a hard day of work associated with grueling physical labor; with heat 30+ degrees Celsius. Here, a cold shower will be a thrill. Infa 146%)
From my own experience of daily dousing ...
The main thing - no matter how you want to reflexively - not to tighten, but, on the contrary, to relax all the muscles. Not a medic, I don't know why - but it immediately becomes much easier.
And yet - try to want more of this cold water, feel pleasure from it. Difficult, but possible :)
If this problem persists, buy a shower head that has a spray mode. This is when water is thrown out in the form of fine dust. Once it just saved me when in the shower right in the middle of washing (when I was just soaping up) they turned off not hot, but cold water. And almost boiling water went (and this, you see, is worse).
You can, firstly, warm up well the room in which you have to take a cold shower (if possible), and secondly, do not get under the stream, but collect water in your hands and wipe it off, it is much less cold and you can still fully wash yourself.
Washing under a cold shower is very uncomfortable, hands are cramped, soap freezes and does not foam stick to the skin and is hard to wash off, hence the desire to die is quite natural.
It is better to pour cold water over it. It is optimal to do this in the morning. The water should not be too cold 15-20 degrees is enough. It is better to start with a contrast shower, stand under warm water, then under cold water it will be much easier to get involved. If you do this every day, then in a month you will not be able to live without cold water).