OK, so today isn’t the start of the new year, traditionally the time when we vow to change our slothful ways. It may not be the start of a new year, but you should think of it that way.

Starting today and continuing through the end of the year, our lives tend to change. This afternoon around 2, there’s the turkey, the dressing, the mashed potatoes, the sweet potatoes, the cranberry sauce, the pecan pie, the drooling, the nap. Repeat around 6 p.m. and again at 11. Figures very wildly on the total damage done on Thanksgiving Day, but the American Council on Exercise believes the typical American consumes 3,000 calories during the main meal and 4,500 calories over the course of the day. That’s more than twice the recommended daily caloric intake for the average American.

And things don’t slow down much through the holidays, with the endless neighborhood parties, office get-togethers, school functions and time spent in the mall, where we rely on the food court to fuel our holiday shopping. The cumulative damage isn’t as bad as urban myth would have us believe: a 2000 study by the National Institute of Child Health and Human Development and the National Institute of Diabetes and Digestive and Kidney Diseases found that we gain about a pound, on average, over the holidays, not the commonly believed five to 10 pounds. But that’s an extra pound few of us need and one that the study says few of us will lose. Cumulatively, the effect of the holidays can be severe.

So why not take action before the holidays, rather than wait until January 1? Here’s the plan …

This morning, after breakfast but before the day gets rolling, take a walk. Around the neighborhood is fine, a trip to a local park is even better. Walk for a minimum of 30 minutes, an hour if the weather’s nice and you’re inspired. Later, after dinner, during half-time, take another, shorter walk. Around the block is good. Do this and you’ve accomplished two things. One, you’ve likely reduced your appetite. Sounds crazy, you are burning more calories, after all. But a moderate walk tends to lessen the desire to eat. The second walk should help suppress that late-night desire to gnaw the turkey carcass to the bone.

The other thing you’ve done by incorporating exercise into Thanksgiving Day is establish a routine, because tomorrow you’re going to do the same thing. Assuming you have the day off, walk for 30 to 60 minutes in the morning, take a shorter walk in the late afternoon or evening. Repeat on Saturday and Sunday. Come Monday, around the water cooler at work, you’ll find you don’t have much to contribute when the topic turns to, “You won’t believe how much I ate the last four days!”

The challenge comes when you try and maintain this new regimen as you return to work and the real world. The solution: Don’t try. This is a crazy-stressful time of year; pushing yourself to walk for an hour or so every day isn’t realistic and will have the worst possible outcome: You’ll resent what’s supposed to be making you feel better.

Instead, vow to walk four times a week through New Year’s Day. Try to make each walk a minimum of 30 minutes, but don’t fret if you discover you can only spare 20 minutes for one session. You know your schedule best, but try to work in two walks during the work week. Lunch is an especially good time since it’s warmer (though since it’s winter, not so warm that you work up a … glow when you return to your workspace) and, again, the appetite suppressant thing. Save two walks for the weekend when, presumably, you have more time and can walk a little longer. Repeat weekly through the end of the year.

You will not lose 10 pounds with this five-week program. You will not lose four inches inches from your waist nor will you drop three dress sizes. And you will not emerge on January 1st with six-pack abs and a Reebok butt. But you will survive the holidays in relatively good shape. And, and you will have done something even more important: You will have proven that you have the discipline to exercise regularly, that you can carve time for a workout from your hectic schedule and that sweating really isn’t such a bad thing.

You may even discover you like it.

Photo: Of Kramer, Calvin Klein once observed: “His buttocks are sublime!”