Several times during your busy day, put down what you're holding--your shopping lists, your third cup of coffee, your date book, the phone call you should be making--and sit quietly for just 60 seconds. Take in a full breath, let it pool gently in the bottom of your lungs, and then release it slowly. Inhale deeply again, and exhale with an audible sigh.
Inhale again; exhale with a long "aaahh." With each exhalation, let your shoulders drop and your jaw relax. Do this a couple of times, with your eyes closed. Let the "aaahh" sound emerge from your belly, move up into your heart, and drift out into space as you exhale, slowly, smoothly, steadily.