But if you're worried all that non-activity, coupled with too much Christmas cheer in the form of food and drink is going to take its toll - not just on your already-dwindling fitness levels but on your waistline too - fear not. We've come up with some suggestions for how to burn off all those mince pies, but in a fun, festive way (with no gym or dreaded Wii in sight).
Shopping Yes you can burn calories while doing your Christmas shopping - about 144 per hour for the average-sized woman, apparently. Not bad for something that brings so much pleasure to so many. Just make sure you don't spoil all that effort by guzzling full-fat hot chocolate drinks or lattes between department stores.
Dancing with your gran Of course it depends how much energy you put into it, but a Christmas evening boogie in front of the fireplace with friends and family could see you burn up to 300 calories if you stick at it for an entire hour. That's around five chocolate box choccies taken care of then. Result.
The post-Christmas lunch walk Yes we know it can be a pain if there's something good on the telly, but the traditional afternoon walk with the dog on Christmas Day burns up to 200 calories an hour. And if it's really chilly, you'll burn even more, as the colder it is outdoors, the harder your metabolism has to work to keep your body temperature normal.
Playing Twister Forget the more passive board games like Monopoly and Trivial Pursuit, Twister's what you need if you're going for a bit of a calorie burn (up to 170 per hour, and you'll get a good stretch too).
Karaoke Belting out a karaoke hit gives your upper body a workout, including your lungs and heart. And you can burn up to 130 calories an hour too. Just try to stay in tune.
Watching TV No, really. If there's a hilarious comedy on the box, having a good giggle can burn calories - around 40 cals per 10 minutes of uncontrolled laugher.
How are you going to stay fit this Christmas?