Exercise, for all its benefits, is seldom a bundle of laughs. But what if you could ditch the gym and hit a comedy club instead to make health gains? In a study by Lorna Linda University in California, volunteers who watched 20 minutes of stand-up routine dramatically reduced their stress hormone, blood pressure and cholesterol levels, and increased levels of cells related to immunity. "The body's response to repetitive laughter is similar to the effect of repetitive exercise" says lead author Lee Bark, DrPH, MPH.