I take up running in the winter. I also go to Spin class to keep up the muscle memory--it's fun because a lot of people I ride with in the summer go to the same class. And then I go snowshoeing or snow shoe running. I used to ski, but there was no where really close to us and I didn't want to drive a long way every time I wanted to do something active. Snow shoeing is great. Plus, there's no skill involved in it other than knowing how to walk so its easy to pick up.