Ahhh, winter: darker skies, lower temperatures and a heapin’ helpin’ of snow, freezing rain or frigid wind. Who’s up for a 5-mile run? Sure, it can be tough to get out of bed and tougher still to get out the door. But there are good reasons to keep up with your usual outdoor exercise routines, or even to create new ones. While you can get a fine workout indoors at a gym, running track or yoga…