What a difference a week makes! The last Sunday in November, short sleeves and shorts were good enough for my morning 22K outing with the regular running group. Seven days later and winter — such as it is in southern Ontario lately — snuck past security and crashed the party. Slipped in under the cover of a few mild days.

Temperatures a little below freezing coupled with a bit of a breeze meant the high-cut shorts would give way to winter gear to protect me from the elements. Not that there's anything wrong with that.

Exercising in the cold is no big deal. In some ways, I actually prefer it — especially to trying to slog through one of those stinking hot days of summer.

You sweat less in the winter. That's key for someone like me who regularly drops six to nine pounds on a long Sunday run.

Some snow on the ground can be good — as long as it's not hiding a patch of ice. You can actually see and be seen better when there's a bit of snow as it reflects light, making your nighttime runs a little safer.

But what gets me is the reaction from my sedentary friends, who can't believe anyone would want to venture outside on a cold day just to get in some exercise.

"What about all that cold air?" someone invariably asks. "Aren't you afraid that your lungs will freeze?"

Cold air does not freeze your lungs.

Your body normally maintains a temperature of 37.0 C — and it's a bit of a trip from your nose or your mouth to your lungs. By the time all that fresh oxygen is filling up your bronchi and bronchioles in the deepest corners of your lungs, it's warm as toast. Just like the carbon dioxide you exhale — the breath that you can see on a cold day.

And it does get you out of the house. Spending the winter in front of the TV could be bad for your waistline. It doesn't take much to add a whole lot of weight to your frame.

Add just one potato chip every day to your diet — about 11 calories — without increasing your activity, and you're looking at adding a pound of fat a year. Keep it up for a decade and you've expanded by 10 pounds — that's without adding all those extra calories around all those food-centred holidays.

As long as you're properly prepared, exercising in the cold is no big deal. Wearing a couple of layers of proper winter exercise clothing is key. You lose most of your body heat through your head and hands, so a hat and gloves go a long way toward keeping you warm.

The toughest part of a winter workout is getting your cozy butt off the couch and out the door. You'd be surprised how quickly you warm up on even the coldest days.