Laughter is the best medicine. It turns out there’s science to back up that old adage. Research has shown that a good belly laugh on a regular basis is as effective at lowering blood pressure as medication. Dr. Michael Miller directs the Center for Preventive Cardiology at the University of Maryland School of Medicine. He’s also the author of “Heal Your Heart: The Positive Emotions Prescription to Prevent and Reverse Heart Disease.” And his prescription doesn’t require a trip to the pharmacy. “We’re looking at about 5 to 15 minutes of laughter that either brings tears to your eyes or after the laughter episode is finished, you feel relaxed,” he says.