Shoveling snow dressed in winter clothes is only going to get me the exercise.....
It wouldn't matter if you'd do it shirtless. There isn't enough strength in the sunlight in the winter at our northern latitudes. Vitamin D is fat soluble, so you can build up the supplies in your body during the summer, but those supplies will be depleted as winter goes on.
I don't take vitamin D in the summer, but when winter gets going I start taking some. I then gradually ramp up how much I take as winter progresses.