Take a moment and think about where you will be in five years. What will change between now and then? What will you gain? Most importantly, if you had to guess, will you be more satisfied with your life than you are now?If you’re under 40, odds are you answered that last question with a resounding “yes!” You’re facing the future with your eyes wide open and it looks great. But hang on a sec. You might want to take off the rose-colored glasses every once in a while for a clearer view. While we’re often encouraged to find life’s silver linings, evidence is mounting that a little negativity can go a long way toward a longer, healthier life.MORE: How a Bad Mood Boosts CreativityWhen a research team led by psychologist Frieder Lang, Ph.D., from University of Erlangen-Nuremberg analyzed life satisfaction ratings of about 11,000 German adults ages 18 to 96, they found that young people were the most optimistic, regardless of sex, education level or career. The older the participants got, the more pessimistic they became—usually accurately. The naïve youth expected to be happier in five years, but didn’t meet those expectations, while the middle-aged participants best predicted what lay ahead.The scientists then uncovered a quizzical trend: For the senior generation (65 and over), higher expectations were associated with higher risks of disability and death within the next decade. For each increase in overestimating future life satisfaction there was a 9.5 percent increase in reporting disabilities and a 10 percent increased risk of death. The flipside, the researchers wrote, is that “Foreseeing a dark future is beneficial for survival.”Can negative thinking really help you live longer? It’s a hypothesis scientists refer to as the “dark future” or “defensive pessimism.” The idea is that lower expectations help people prepare for the worst, thus making them better at handling the curveballs thrown our way. According to Lang, pessimism about the future may encourage people to live more carefully, taking the necessary precautions with regard to their health and safety.MORE: Escape Others’ NegativityWhile pessimism seemed to pay off for the older adults in this study, it’s important to keep in mind that the connection between pessimism and better health is just that—a connection. What it doesn’t say is that becoming a total cynic will improve your future health. “Pessimism alone is not the answer, nor is anything else in isolation from other factors,” explains Leslie R. Martin, Ph.D., a leading expert on longevity and co-author of “The Longevity Project.”The results by Lang and his team echo previous findings. In a massive eight-decade project, Martin and her colleagues found that the most cheerful, optimistic kids lived the shortest lives. “Many people (including us!) were surprised when we discovered that.” In her research, she has found that a moderate level of anxiety isn’t bad, and can actually be protective. “Certainly excessive pessimism can be bad,” says Martin. “There’s a lot to be said for having a balanced view. Positive thinking can be good, but so can a more pessimistic approach.”QUIZ: Is Your Body Image Affecting Your Mood?Before you go about thinking the worst, keep in mind that Lang and his colleagues found optimism was associated with poor health, but they didn’t find that being overly negative helped. There was no difference between those that accurately predicted their future satisfaction and those who strongly underestimated it. So while it might be good to temper your enthusiasm with a little dose of reality, there’s no need to go overboard and become a total grouch.Strike a balance: a hopeful outlook that acknowledges and prepares for possible future problems. The best strategy, Martin explains, is to “connect to other people, pursue your passions, and persist when the going gets tough.”