Dr. David Neiman of Appalachian State University adds another layer to this, saying that after 90 minutes of high exertion- like long distance running- our defenses instead go down, opening us up to sickness for up to 24 hours following exercising. So the key here is not to wear yourself out and inhibit your body's defenses.

oga is a great option for reaping these benefits, since each person practices to his or her own ability so as not to be hard on the body. The meditative aspect of practice serves as a one-two punch by helping to manage stress, which we know only impedes the immune system further. In addition to lowering stress levels, yoga has been lauded for centuries for improving strength, posture, flexibility, concentration, heart and lung health, and so much more.

The implications of the study are that one is exercising for at least 20 minutes on each of those 5 days, so whether you can attend an hour class or practice at home for only a half hour, most of us can certainly find the time. Even 15 minutes at the beginning and end of a busy day is great. Alternating days of yoga and cardio is also a great option to vary your routine, and in return, your fitness benefits.

Where else besides yoga class can you go to stay in shape, flu-free, and sane this holiday season? There's nowhere better.

In peace and health.