Has anybody else tried it and got used to the cold?
I should add that I always got easily cold and there is almost no temperature where I say that it's too hot.
Did you ever ask a doctor about this? Especially an endocrinologist. One example of many possibilities: https://en.wikipedia.org/wiki/Hypothyroidism
As for cold showers, I dreaded them but at some point in my life I just relaxed. I would call it "acceptance", in general, life throws bad stuff your way and all you can do is "exist", i.e. nothing, really. So if I want to or have to have a cold shower (e.g. when hot water was out once) I just turn on the cold water and get in and accept that it's uncomfortable, especially at the very beginning. Nothing I can do about it - and, more importantly, since I know it's only uncomfortable but not threatening, nothing I have to do. All I have to do is stand there and do nothing and feel whatever there is to feel. At that point I'm just an observer of my own body, with no active role to play. The conscious part does nothing, the forces at play are all controlled by lower level brain functions.
it's done a lot of great stuff to me. winter depressions are a thing of the past to me now, and I'm almost as outgoing in the cold seasons as in summer.