It’s not just your imagination: When the weather cools off, our bodies start trying to conserve energy to use as heat. We eat a little more and exercise a little less. Unfortunately, this natural survival strategy is also a surefire way for packing on a few extra pounds during the winter.

But winter doesn’t have to be the season of sloth. There are plenty of cold-weather activity options suitable for most people. Some of them don’t cost a penny, and even those that do don’t have to be expensive. Check with your doctor before starting any new physical activity, especially outdoor exercise, which can aggravate some conditions.

Take the stairs.
At home or work, spend 20 minutes walking up and down stairs for a workout that’s more vigorous than you might expect.

Clean your house.
Washing windows or floors can burn about 350 to 450 calories per hour for women and men, respectively. Even light housework can burn calories.

Use exercise videos.
Many local libraries have collections of exercise videos or DVDs. Some cable and satellite TV systems have exercise shows you can watch on demand, or you can record fitness shows on any TV station to use at your convenience.