I looked up and found out that shoveling snow by hand for an hour (on a 150 lb. person) burns 408 calories!
Dance Dance Revolution burns about 640 calories in an hour. I'd say that you're doing an excellent thing for yourself! Not only are you being productive, but you're having fun and mixing things up which increases the likelihood that you'll stick with working out in the long run! Don't feel guilty! Our bodies need to be surprised!!!