My number one concern about running in winter is the weather. I am a cold natured person to start with so I like being prepared and comfortable. While browsing Pinterest I found this great infographic by SparkPeople on how to layer up properly for running. It showed me that even though it feels chilly out, all I need for a 45 degree winter day is a base layer long sleeve shirt, a pullover or sweatshirt and running pants. No need to bundle up like a snow bunny when you are about to expend energy and heat things up!