The cold, wet, snowy Winter months can definitely make running on a treadmill much more appealing than the great outdoors. There are advantages to both running locations, but one disadvantage of using a treadmill is the belt. The backward motion of the belt assists you by pulling your feet back underneath your body, which means you are exerting less energy to move your feet and legs than when running outdoors on a surface that doesn't provide any momentum. However, you can work your legs more by imagining that you are pulling the belt back with your hamstrings. This idea helps me feel like I am digging in my foot and accessing the power of my hamstrings, which really work to push the body forward when running. The treadmill can get pretty boring, but with this little trick, you have something else to focus on besides watching the clock, and you're building hamstring strength. I call that a win-win situation.