The late President Ronald Reagan was known as an eternal optimist, writes his widow Nancy in this week's Time magazine, who considered one of his greatest achievements to be "giving the country back its optimism." For Reagan, "the glass was always half full," she adds. "I think his faith and his comfort with himself accounts for that optimism."

For those of us with a pessimistic turn of mind, such optimism may seem to be either out of reach or out of touch with reality-just too darn sunny for words. But it turns out that optimism is one of the keys to living a happy life. For one thing, it helps people bounce back when adversity strikes. It's a core element in remaining hopeful even in the most dire circumstances. It's an essential factor in both perseverance and creativity (when you're in a good mood, you're more creative). And medical research shows that optimists are more likely to recover from heart attacks and the common cold. Most of all, optimism staves off depression. All in all a trait devoutly to be wished for.

But what if you weren't lucky enough to be born with that "optimist" gene? Not to worry. Researchers at the University of Pennsylvania have been studying optimism for nearly 30 years. It turns out that optimism can be taught. You, too, can learn to turn lemons into lemonade.

"Optimism certainly is a core element in super-resilient people, of whom Reagan was one," says Dr. Karen Reivich, a research associate in Penn's Department of Psychology, where she co-directs a program to study the prevention of depression and promotion of resilience in children. "We know that optimists perceive the world in a certain way. Early on in our study, we broke optimism down into several key thinking styles."

These three thinking styles affect how you interpret events-especially negative events-in your life. While all of us fall along a continuum, find your characteristic tendencies in the following thinking styles:

"Me vs. Not Me": Who's to blame?
When things go wrong, is your tendency to blame yourself or to look outside yourself for the causes of problems? If you blame yourself excessively, you're more likely to be pessimistic. (Caveat: We're talking about unrealistic levels of self-blame that paralyze you from further action, not realistic taking of responsibility.)

"Always vs. Not Always": Is the problem permanent or temporary?
When things go wrong, do you believe the problem will last forever and that you can't change it? Or do you believe that the causes are fleeting, or at least something you have control over? Those who believe that latter are more optimistic.

"Everything vs. Not Everything": Is the damage pervasive or limited?
The "everything" people are pessimists. They believe that a problem will spill into every domain of their life and have consequences throughout their world The "not everything" folks (optimists) are good at localizing the specific adversity and containing it.

Research shows that people with a "me, always, everything" mindset tend to blame themselves when things go wrong, think the problem is completely outside their ability to change, is lasting, and will undermine everything they do. Down for the count.

"The nice thing is that those styles are changeable," says Dr. Reivich, who is also coauthor of "The Resilience Factor" (Broadway Books, 2003). "If you're a person who tends to blame yourself when things go wrong, I can teach you some simple cognitive techniques to retrain your mind-not to dismiss your contribution to a problem but to say `I'm also going to look outward at what other factors were involved.' It's a question of seeing the world and yourself as positively as possible, but within the constraints of reality."

Learning the Skills of Optimism
We all have an internal radio station, says Dr. Reivich, that plays nothing but "us" 24-7. We're the announcer and we're the listener. But most of what we say about ourselves is at a low volume. The first step to retraining our minds is to turn up the volume.

Step One: Capture what you say. Listen to your internal radio station. Even though you're not aware of it, your thinking style-what you're saying to yourself in the heat of the moment-is having a big effect on your mood and behavior. So listen for recurrent patterns of "me, always, everything."

Step Two: Challenge that voice. Pessimists believe with great certainty that the negative way they see the world is correct. So be skeptical and ask if there is another way of seeing this situation that will get you closer to your goals. Just because you're saying it doesn't make it true.

Step Three: Generate alternatives. If you're job-hunting and didn't get a call back, you may notice the voice saying, "This proves it! I don't have any skills, no one's going to hire me ever. I might as well give up." These are "me" and "everything" styles of thinking. Instead find one reason that's "not me": "It's a tough job market out there, but I only made ten calls. If I make twenty more calls, I'll see results."

Step Four: Put it in perspective. This essential skill counters anxiety. This is for when you wake up at 3 A.M. and experience a cascade of dire events-let's say you failed to meet a deadline in your office. You've gone from "I forgot to mail the brochures" to "I'm going to get fired, I'll never find another job, I'll lose my home and live in poverty for the rest of my life."

Get a sheet of paper, make three columns, and write down "Worst-Case Scenario" and "Best-Case Scenario," leaving one column in the middle for "Most Likely Outcome." Write down your biggest fears and then make a list of equally unrealistic best hopes (e.g. "There was a terrible mistake in the brochure, so it was a blessing I didn't send it out. I'll get a raise.") The extreme scenarios are so ridiculous they can jolt you out of your catastrophic thinking. Then you're ready to fill in the space for "Most Likely Outcome" ("My boss will be a little annoyed. I'll have to work this weekend.")

Now go back to sleep.

Step Five: Have faith. Nancy Reagan was right. There's a definite relationship between optimism and faith. A certain kind of faith provides an enormous sense of hope, an assurance that even if things aren't going well, there is a pathway through the darkness. Things will get better.

Step Six: Reach out to others. When you find yourself brooding on things that happened to you, it helps if you have someone to turn to who can challenge your pessimism. It's easier for an outsider to question your beliefs because he's not caught up in them in the moment. A spouse, partner, friend, or therapist can help.

Step Seven: Find small things that make you feel hopeful. Many of us are experiencing a crisis of pessimism these days-feeling that the world is spinning out of control. The best antidote is to turn off CNN for a while and notice small instances of beauty, goodness, and blessings around you. If a flower bloomed in your garden today, or your children came back from school thrilled about summer vacation, or someone did you a kindness-focus on these things. If you think that sounds too simple, just try it. Give life's modest, daily pleasures a chance to wake you from despair and bring out the optimist in you.