'Tis the season. The season for the common cold -- that unwelcome guest in the midst of the festivities.

But you don't have to let sniffles spoil your holiday fun. Adding a little sweat to your day may help keep colds away. A new study shows that a 45-minute workout each day, 5 days a week, lowers the risk of catching a cold. And the longer you stick with a regular exercise program, the better the benefits. So dust off your walking shoes and start building up your immunity.

Past research has hinted that moderately intense activity is an immunity booster, but those studies were too short to be convincing. More recently, and for the first time, researchers took the long view and studied two groups of women -- one basically sedentary and one not -- for a year. And the results are truly motivating: Overweight couch potatoes who started exercising and stuck fairly close to their five-times-a-week workout program had a definite cold-fighting edge over a similar group of women whose regular exercise consisted of just a weekly stretching routine.

You may already be enjoying the benefits of a revved-up immune system if you are a regular exerciser. If not, get crackin'. You'll enjoy knowing that your sweat is helping ensure that you won't be sidelined by sniffles and sneezes during next year's holiday fun.