Go to the science channel on Feb 7th, 5pm, and watch: “Cold”
http://science.discovery.com/tvlistings/episode.jsp?episode=1&cpi=65952&gid=0&channel=SCI
After watching this it took one of those large hot packs and put it over my heart when I was out in a layout blind in 0 degree weather. It really works!
The Fat Man