Stumbled upon this article about cold showers being healthy - Health benefits of cold showers. I didn't realize cold baths were thought of so highly in times past!
Reminded me of Wim Hof "The Iceman" who has proven in multiple studies that he (and people he trains) can influence their autoimmune system to stave off cold and disease.
Surviving the cold is sort of understandable because the training Wim offers is specifically for the cold. What is surprising is withstanding disease as well. I wouldn't have expected that from being exposed to cold! It's precisely the opposite thing that grandmothers everywhere have been telling their children for as long as I can remember.