Hmm. Perhaps the previous posting needs a bit of explanation ...
Years ago, I read a book on Tibetian yoga, in which there was a discussion of the lamas who practiced tumo. This is the ability, essentially, to run a fever at will, so that in extreme cold, one could generate warmth. Altering one's body temperature by this process isn't supposed to be one of those voluntary-control things one can do, but they were able to do it.
In one experiment by western science, if I recall it correctly, a yogi was able to draw a line down the center of his palm and make his skin measurably warmer on one side than the other. (I believe it was the Doctors Green, a husband/wife team who did this research at the Menninger Clinic.)
One of the tumo tests was to sit in the cold next to a frozen river. A hole would be chopped in the ice, and a towel (actually the size of a bath washcloth) would be dipped in the cold water and then laid on the bare back of the person being tested. The goal was to dry the cloth out by generating internal heat. Supposedly the tumo practitioners could dry out three of these in a relatively short time, one after another.
Conversely, there was a meditation for cooling, wherein the practitioner could sit in a circle of bonfires in relative comfort. Probably not as useful in Tibet, but there you go.
For a time, I played with the concept, and was able to half-assedly use it on cold days. (It takes a fair amount of concentration. My skill has lapsed considerably -- and I never was able to make it work very well on my hands -- so that jogging in shorts and a T-shirt, or recent winter session in Guru's unheated garage sometimes require that I wear thin gloves.)
One of my tests was, on the infrequent occasions when it snowed, was to sit briefly in the snow nekkid, just to see if I could still do it.
I still can. But not for long. And drying out the wet cloth? No way.