NEW YORK (Reuters) - The short days, the weak sun, and the warm beds of winter can wreak havoc on your fitness routine. As the outside temperature plummets, so too can the will to brave the elements for outdoor exercise. Experts say as long as you layer up, drink up and tune into how cold is just too cold it shouldn't impact your fitness. "Come with a different game plan for the winter," advises Jessica Matthews, an exercise physiologist with the American Council on Exercise (ACE). "Motivation tends to wane a bit, so explore different activities, including things you can do in your own home. ... read more..