What should I wear if I want to jog outside in the winter? Is it better to layer, or should I just put on a warm pullover? 
— Eric, Illinois

It's always a challenge to regulate your temperature when you exercise outside in cold weather, but my advice is: layer, layer, layer. Remember that your body can produce a lot of heat once you start jogging, so you have to dress appropriately. I like to put on two or three layers of clothing, and I'll typically strip the top layer off as I begin to warm up but before I have started to really sweat.
I not only like layers, I like lots of zippers. A warm piece of clothing that has zippers is a nice strategy for controlling your temperature without have to wear and remove several different layers of clothing. Simply open up zippers as far as you need to in order to feel relief as you start to heat up.
Also, avoid wearing cotton clothing. Cotton traps water close to your skin, which becomes very cold when exposed to frigid air. You need breathable fabrics that wick water away from your body and then allow the water to evaporate. Several manufacturers of athletic apparel offer clothing made of high-tech fabrics that are ideal, so check the tags when you shop for your next jogging outfit.