The breathing is something that one has to discover for oneself to a degree. 30 breaths in/out through the mouth are more of a guideline.

You would be suprised how fast you get used to cold showers. And they actually feel great afterwards. After having taken a cold shower in the morning, I am awake but relaxed. I also found that sleeping was overall better after a cold shower in the evening.

I only stopped the breathing but I still take cold showers. I am much less cold-resistance than I have been back in 2016, that is for sure. But I still hold my own a bit better than I would have before I started.