We've heard the stories about the healing power of laughter. Scientists are now "graphing the laugh" and it's a serious subject. They've discovered that even animals laugh (no, not just hyenas). In the research lab, rats would continue to return to handlers who tickled them. Dr. Robert Provine, author of Laughter: A Scientific Investigation, studied laughter for years and concluded that laughter is mostly social and only a very small percentage of laughter is a result of joke telling. Laughter can actually produce a chemical that acts as an anti depressant in the brain. While there is no scientific evidence that laughter alone produces a direct health benefit, it's enough that laughter feels good and creates good feelings. So don't stress yourself if you can't tell a joke. Laughter is about engagement. You can project a funny cartoon, show a humorous video clip or even play off the humor of the audience. All you need to create laughter is another person. Nervous? Laughing is a good way to burn off nervous stress. Facing a hostile audience? Get them laughing. You can't be angry and laugh at the same time. So stop being so serious and bring a little laughter into your presentations.