According to a recent TIME Magazine poll, the percentage of Americans who identify themselves as “optimists” has plummeted from 79 percent in 2004 to 50 percent today. Count me among the optimists. In 2004 Facebook was the brainchild of a group of Harvard friends and limited to students. Twitter didn’t exist and LinkedIn was in its infancy. Devices like the iPhone and iPad had yet to reinvent business, medicine, and entertainment. And this doesn’t even touch the huge decline in childhood mortality around the world and the radical advances in science and technology that have occurred in past decade. Give me 2013 over 2004 anytime.

Despite the overwhelming evidence that America (and many parts of the world) are getting better—significantly better— there will always be people who are outright pessimists or, as the TIME magazine poll revealed, those who consider themselves “somewhere in between.” If you’re a leader who hopes to inspire his or her team, it’s critical that you’re not one of them. UC Santa Cruz professor, Dr. Martin Chemers, has studied leadership and effectiveness among corporate chiefs, military leaders, and successful managers. He finds that confidence and optimism are two important qualities that set leaders apart from followers. He calls these qualities “mettle.” His studies have found that optimism is an essential ingredient in a leaders’ ability to rally people behind their vision.

Leadership author Marcus Buckingham once said, “The opposite of a leader isn’t a follower; the opposite of a leader is a pessimist.” But what if you’re currently among those who label themselves “pessimist” or who can’t make up their mind? Good news. Psychologists have discovered that, to a large extent, optimism can be learned. Here are five ways to build your optimism muscles.

Build on your strengths. Optimistic leaders focus on their achievements. They learn from setbacks. There are no failures; just results. In this previous column, I discuss how the mental coaches of professional golfers help them achieve a peak mental state. The difference between a 16-handicap and a scratch golfer is that the high handicapper focused on the putts he missed instead of the putts and shots he hit well.

Radiate optimism. If you show signs of confidence on the outside, you will feel more confident on the inside. Paul Ekman, a famed researcher in the area of nonverbal communication, discovered that when you frown, you will eventually feel sad. If you smile, stand up straight, and walk with purpose, you’ll actually feel happier. Your demeanor rubs off on others, too. During the sustained bombing of London in World War II, Winston Churchill told his staff to always be seen with a smile on their face and a spring in their step. He understood the outward display of optimism would make his staff and the people of London feel more confident.

As a leader, your mood infects others. The concept is called “emotional contagion” in the academic literature. It means that a positive or negative attitude spreads. A team grows more confident, productive, happy, creative, and engaged simply by being in the presence of a positive person who radiates happiness, joy, and an unflinching belief that things will get better.

Think highly of yourself. Words have power—the words you speak to others and the words you say to yourself. In this column titled, How Warren Buffett and Joel Osteen Conquered Their Terrifying Fear of Public Speaking, I discuss how both leaders grew more confident as they reframed their thoughts. In the March 2013 issue of The Atlantic researchers found that the benefits of optimism are real. It seems as though a positive outlook is the most important predictor of resilience, an essential ingredient of leadership. According to the article, “When your mind starts soaring [reframing challenges into positive opportunities] you notice more and more positive things. This unleashes an upward spiral of positive emotions that opens people up to new ways of thinking and seeing the world — to new ways forward. This is yet another reason why positive people are resilient. They see opportunities that negative people don’t.”

Surround yourself with builders, not detractors. Speaking of Warren Buffett, he recently offered this lesson for success: “If you tell me who your heroes are, I’ll tell you how you’re going turn out…You want to hang around with people that are better than you are. You will move in the direction of the crowd that you associate with.” This reminds me of something Oprah once said: “Surround yourself only with people who are going to lift you higher.” If you hang out with pessimists, they’ll drag you down. Psychologists call the concept “zone of proximal development.” Simply put, your potential is largely stifled or enhanced based on the skill level and attitude of those you choose to include in your inner circle.

Create magnificent obsessions. Optimistic leaders dream bigger than most people. Several years ago I had a conversation with Starbucks founder Howard Schultz who said if you’re going to dream, you might as well dream big. His partners at the original Starbucks were content with selling coffee beans. Schultz dreamed of creating an experience; a third place between work and home. He left the original Starbucks, started his own coffee chain, and eventually bought and built Starbucks into the chain we know today. A big, bold vision unleashes creative forces and inspires like-minded people to follow you.

Pessimists don’t make great innovators. In this opinion piece for the Wall Street Journal, Bill Gates, who calls himself an “impatient optimist,” said pessimists are often wrong because they assume the world will continue as it is. “They simply extrapolate from what is going on today, failing to recognize the new developments and insights that might alter current trends,” Gates said. You cannot afford to a pessimist and neither can your business. The world needs optimists to move it forward. Be an optimist and inspire others to join you.