JULIA HENSLEY, a 41-year-old artist, got a taste of bitter cold a decade ago when she spent a winter living on a glacier near Seward, Alaska. Typical winter temperatures were 10 to 15 degrees below.

“The first time it got really cold, I was scared of it,” Ms. Hensley said. “My instinct was to get a stack of books and curl up beside the wood stove.”

But a boyfriend persuaded her to go out anyway, to cross-country ski or snowshoe for hours in deep snow. He taught her, she said, that as long as she kept moving, she would be fine.