Another one here. Mostly I have trouble if I'm less active, although once I get cold, I will not warm up no matter what I do, short of a total immersion hot bath. I have a terrible time at seminars where they tend to set the AC at 70F or below - my thumbs and fingers get numb and painful. Before we started flying south for the winters, my toes would be blue (literally) from December through April.

Same thing with the heat (95F and above) - difficult and dangerous for me on the motorcycle (moderate exertion), have to wear a cooling vest; no real problem on the bicycle. Hydration has a lot to do with that, I know - I get dehydrated very, very easily to the point where I can't absorb plain water and have to drink hydration solutions - but I really don't think that's all that's going on, considering I have trouble with the cold, too.

Faulty thermostat, is all. Someone told me once that the kidneys are the thermostat of the body; I have no idea whether that's true or not.