What keeps us happy and healthy as we go through life? If you think it's fame and money, you're not alone – but, according to psychiatrist Robert Waldinger, you're mistaken. he Harvard Study of Adult Developmentmay be the longest study of adult life that's ever been done.For 75 years, we've tracked the lives of 724 men,year after year, asking about their work, their home lives, their health,and of course asking all along the way without knowing how their life storieswere going to turn out. So what have we learned? What are the lessons that come from the tens of thousands of pages of information that we've generated on these lives? Well, the lessons aren't about wealth or fame or working harder and harder. The clearest message that we get from this 75-year study is this: Good relationships keep us happier and healthier.We've learned three big lessons about relationships.The first is that social connections are really good for us,and that loneliness kills.It turns out that people who are more socially connectedto family, to friends, to community,are happier, they're physically healthier, and they live longerthan people who are less well connected.And the experience of loneliness turns out to be toxic.People who are more isolated than they want to be from othersfind that they are less happy,their health declines earlier in midlife,their brain functioning declines soonerand they live shorter lives than people who are not lonely.And the sad fact is that at any given time,more than one in five Americans will report that they're lonely.