Well, it’s January 4, and I’m back in the office after a fantastic and frenzied, friend- and family-filled holiday break. But rather than feeling rejuved and reinvigorated, I feel frumpy, sluggish, tired and slightly irritable.

Why the shlumph? No mystery here: During the past month, I ditched grilled chicken, spinach and squash in favor of frequent pizza pig-outs, nightly (and morningly) cookie and fudge feeds, and many more glasses of Malbec than one needs to complement cheesy scalloped potatoes. I hit the gym only a few days each week, and I slugged through each workout as if it were punishment. What’s more, the days were (and still are) short and the sunlight sparing, making me melancholy and more inclined to huddle by the fireplace and thumb through magazines than strap on the YakTrax for a twilight run.

And there you have it: Not-so-healthy food plus not-so-much movement plus not enough mood-boosting light equals the inevitable annual abominable post-holiday blahs.

So it’s obviously time to shun the sugar cookies and get rockin’ on the StairMaster. But, unfortunately, even three- or four-week-old habits can be super-hard to kick. Our bodies and minds are creatures of routine, and when we get used to high-fat, low-nutrient foods—even if for just a short period of time—we crave high-fat, low-nutrient foods. When we quit busting lungs and working up a sweat each day, our bodies’ signals to “get moving!” ring a little softer and less convincing than usual. And then of course that whole depressing darkness thing will remain an issue well into March, but there’s little we can do to convince the sun to stay up longer.

So how can I bust through my malaise and kick my butt into gear? Especially when scrumptious leftovers still scream at me from the fridge, every candy dish I pass is still brimming with treats, and the gym is nightmarishly, annoyingly packed with others hell-bent on sticking to their New Year’s resolutions?

Well, after pondering this for a while, I have to admit I failed to come up with anything super-scientific, new or insightful. I’ve heard it all before in some way, shape or form. But I did realize a few key things: First off, I gotta give myself a break. My holiday was stellar, and it’d be a crime to cloud its memory with negativity just because I lack zip in its aftermath. Second, I gotta start small. No, I won’t be able to outlaw all candy and run three miles at my pre-Thanksgiving clip by tomorrow, but reintroducing broccoli and pushing myself a little harder at the gym each day will ultimately make me want to up my veggie ante and run like the wind. Third, I’m one lucky cat to even be contemplating this conundrum, as I have the options of tasty, nutritious food and healthy, happy environments whereas so many people do not. And this reminds me, yet again, to be thankful for what I have and to keep that holiday spirit rolling right into to 2011.