The #1 Holiday Diet and Fitness Mistake You Make

You've been working hard to stick to your regular diet and workout routine during the holidays. You even managed to squeeze in a few early morning workouts to free up your evenings for festive events. One day you walk into the office to find an incredible breakfast spread—gourmet pastries, muffins, bagels, fruit, and more cream cheese flavors than you ever knew existed. It's your boss's way of saying thanks for all the hard work you did this year. You already ate your standard bowl of steel cut oats with sliced almonds and berries, but you don't want to offend your superior so you grab a muffin and eat it as a mid-morning snack at your desk. It's not the best choice, but one muffin isn't going to ruin you. The real problem is what happens next… "Well, today is already ruined. I might as well grab a bagel and cream cheese for lunch. It's free, after all!"

The next day is your annual cookie exchange, which you've already written off as a "cheat day," but you'll get back on track after that. Oh wait. You have that cocktail party this Saturday and plans for Sunday brunch with your girl friends."It's the holidays! I'll enjoy it and just be really

good after New Year's."

Sound familiar? Even if this specific scenario doesn't resonate with you, the general idea of an all-or-nothing approach to diet and fitness might, especially during the holidays. And that is truly the No. 1 mistake you can make. You can (and should) enjoy this time of year, but the secret that those eternally fit friends we all love (or love to hate) know is that it's much easier to get out of a diet ditch than a well. Eat your favorite holiday treat and don't feel guilty (the ditch)! But also, don't follow it up with an entire week of endless gorging (the well).

As for your workout, be realistic and keep it simple. A little exercise most days goes a long way in helping you feel and look great through the holidays and into the New Year. This 20-minute, calorie-blasting routine was designed exclusively for SHAPE by Kasper Allison, personal trainer and owner of Physical Focus in Montecito, Calif. I find it easiest to do in the morning before things get too hectic, but the best time for you is any time you can fit it in.

Do 1 set of the prescribed number of reps for each exercise, moving from one move to the next without resting in between. Repeat the full circuit 5 times. Each exercise should be done with as much power as possible.

You'll need: A medicine ball (10-20 lbs).

Stand with your feet hip-width apart, holding a medicine ball at your chest. Shift your hips back, bend your knees, and lower into a squat until your thighs are parallel with the floor. Touch your elbows to the tops of your thighs, and make sure to keep your chest lifted and core engaged. Press through your heels to return to standing. That's one rep. Do 10 reps total.

Holding the medicine ball at your chest, take a big step forward with your right foot and lower into a lunge. Make sure your front knee doesn't go too far beyond your ankle and your back (left) knee bends straight down to the ground. Press off your front foot to step back to the starting position. Repeat, this time taking a big step forward with your left foot. Keep your chest lifted during the entire movement. Continue alternating legs until you've done 10 lunges on each side.

Lift the medicine ball overhead with straight arms. Forcefully throw the ball straight down as hard as you can. Make sure to keep a slight bend in your knees and do not round your spine. Catch the ball off the bounce, lift it back overhead, and repeat. Do 10 throws total.

Stand with your feet hip-width apart. Shift your hips back and bend your knees to lower into a squat, and then explosively jump off the ground as high as possible. Swing your arms back as you bend your knees and then swing them forward as you jump to help increase your height. Land softly and immediately lower into your squat to jump again. Do 10 jumps total.

Come into a plank position with your hands directly below your shoulders, feet shoulder-width apart. Bend your elbows and lower your body into a pushup. Explosively push up, clapping your hands at the top. Land both hands back to original starting position. Do 10 reps total (or as many as you can with good form).

If this is too challenging, you can do this exercise on your knees.

Stand on your right leg. Bend your knee, shift hips back, and jump as far as possible laterally. Softly land on your left leg with a slight bend in your knee. Shift your hips back and jump as far as possible to your right side. Make sure to keep your chest lifted and land on your entire foot (not just your toes). Continue alternating until you've done 5 jumps on each side.