The worst part was breathing. Practically hyperventilating from the shock of the freezing-cold water, the sensations in my body felt similar to what I’ve experienced during panic attacks. (So, no, this is not fun at all.) About two minutes in or so, though, my breathing slowed down, and I was able to stand still and sham…
You don’t have to go in cold turkey. I took several weeks to get there, turning down the hot water a notch with each shower. That let me acclimate myself so that I can now step in to full cold without any great shock.
I do it “military style”: wet down, water off, soap up, water on, rinse off. Saves water and feels just as good.
And yes, it feels so good to get out.