I am going to commit to doing this again tomorrow, though, because I remember that it makes me feel good.
The same thing happened to me after age 34 for some reason. It's been years so far. I haven't done any breathing exercises though.
Maybe I was doing it wrong but I do not know how - I started with just showering my legs with lukewarm water and progressed to colder water and longer time gradually, very slowly. However, it never made me feel as good as some people here descibe. Sometimes I felt slightly refreshed during the summer but more often I just felt cold and stiff and I had strong desire to return to bed to warm up but I could not do that and I had to sit in my office cold and miserable for hours.
Maybe cold showers are not for everybody?
As in, don't do it gradually.
Drop it INSTANTLY and just see how long you can last, even if it's only a few seconds. I know at first I was like okay, 5 seconds f* this.
But then you can make it a bit of a game for yourself, and after a while it just becomes habit.
(and fyi, I live in Florida, so staying in longer is much easier-- But I can say this switch made me change from dreading visiting relatives up North because that would ALWAYS make me sick --- to "aww yeah super cold showers in the morning," and you know, not getting sick.)
I'm one anecdotal data point:
Never heard of this guy, but the cold shower thing just sounded plausible enough that I figured I'd try it.
Not even the whole thing cold -- I start off with a hot shower and then just drop it for the last minute or so, as long as I can stand.
And -- it's CRAZY. After getting the regular yearly colds that I just presumed were a part of life...they just stopped. I haven't had any sort of cough/cold sickness at ALL going on about 3 years.