Students are flocking to Tal Ben-Shahar's class at Harvard University for some insights into the nature of happiness. So much so that Psychology 1504, or "Positive Psychology," has become the most popular course on campus. Twice a week, some 900 students attend class on what he calls "how to get happy." Mr. Shahar believes he achieved personal happiness by taking himself off the tenure track, the rational being that not having to publish makes him happy. His class offers research from the relatively new field of positive psychology, which focuses on what makes people happy, rather than just their pathologies.

What is happiness?

Happiness is a combination of meaning and pleasure. A happy life is one that has meaningful, purposeful, significant, important experiences. And it's a life that one experiences pleasure in. It's enjoying the journey and the destination.

You cite a study in "Happier" that found 50% of people were unhappy at work. Why is that?

Some haven't found the work that provides them a personal sense of purpose, significance and meaning. More importantly, though, most people fail to appreciate what they have at work. They fail to appreciate the potential for a sense of well-being that exists right in front of them.

Who is happier, the CEO or the clerk?

They're equally happy. That's the thing about happiness. It's the great equalizer between people of different socioeconomic levels, different ethnicities, different countries. The only difference in terms of happiness levels is among countries where there is no democracy, where there is oppression, where there is legalized discrimination.

Who is more responsible for an employee's happiness, himself or his boss?

Both. It's up to the boss to ask the right questions of the employee: "What would give you meaning? What are your strengths?" And cultivate those. But first and foremost it's up to the employee, and very often the employee doesn't take the responsibility. Studies have found that hospital cleaners can enjoy their work more than doctors if they perceive the meaningful part of the work and focus on it. For example, seeing their jobs not just as removing trash and washing dirty linens but contributing to patients' well-being and the smooth functioning of the hospital.

Name one thing employees can do to be happier?

Often people are asked to write a job description. I would urge people to write a calling description. Describe your work to someone who doesn't know what you're doing. What in your work is making a difference in people's lives? You can do that whether you are an investment banker or working in a homeless shelter. When you focus on that, it increases your level of well-being.

What's the relationship between money and happiness?

It's tenuous at best. Once our basic needs -- shelter, education, food -- are met, money makes very little difference to our sense of well-being. A lot of people are under the impression that money will make them happier. They are struggling for more money, a promotion, more prestige and power. The reason there are so many very unhappy, very successful people is that for their entire lives they have lived under the assumption that once they "make it," they'll be happy. Then they get there, and they realize there's no "there" there. That's when they become despondent. That's why so many celebrities are on drugs and alcohol. They've made it, they have all the men and women, and all the money they want, and yet they're unhappy. This model of once you make it, you'll be happy -- it's simply the wrong guiding principle.

There are a lot of people in the world like that. What would you advise them to do?

Happiness is mostly contingent not on our status or the state of our bank account, but our state of mind. What that means is learning to not take for granted the positive and what's working in our lives. It means expressing gratitude, and finding activities that are meaningful and pleasurable. It also means acts of kindness. The more we give, the happier we become, the happier we become, the more we give. It's an upward spiral.

Are Californians happier than New Yorkers?

There's research on this. Californians are not happier than New Yorkers, despite the weather. Why? Because we usually adapt very quickly to the external.

Is Disneyland really the "Happiest Place on Earth"?

Well, their mission statement is to make people happy. I think it's a wonderful thing. It's a happy place. The question is, how to have more happiness in our day-to-day lives, once we leave Disneyland.

Author Walter Mosley has said we should not ask: "Am I happy or unhappy?" but "How important is it to be happy?" What do you say to that?

I disagree. I think one of the most important questions to ask is: "How can I become happier?" It is a lifelong journey and it is an important journey -- as an end as well as a means. In terms of an end, it's good to feel good. It doesn't need any more justification than that. All else being equal, I'd rather be happy than unhappy. But also as a means. Happy people, all other things being equal, enjoy more physical health, and actually live longer. They are more creative, more energetic, more motivated. And they are more generous and benevolent toward other people. So there is every reason in the world to aspire to higher levels of happiness.

Six Tips for Happiness

Advice from Tal Ben-Shahar.

1. Give yourself permission to be human. When we accept emotions -- such as fear, sadness, or anxiety -- as natural, we are more likely to overcome them. Rejecting our emotions, positive or negative, leads to frustration and unhappiness.

2. Happiness lies at the intersection between pleasure and meaning. Whether at work or at home, the goal is to engage in activities that are both personally significant and enjoyable. When this is not feasible, make sure you have happiness boosters, moments throughout the week that provide you with both pleasure and meaning.

3. Keep in mind that happiness is mostly dependent on our state of mind, not on our status or the state of our bank account. Barring extreme circumstances, our level of well being is determined by what we choose to focus on (the full or the empty part of the glass) and by our interpretation of external events. For example, do we view failure as catastrophic, or do we see it as a learning opportunity?

4. Simplify! We are, generally, too busy, trying to squeeze in more and more activities into less and less time. Quantity influences quality, and we compromise on our happiness by trying to do too much.

5. Remember the mind-body connection. What we do -- or don't do -- with our bodies influences our mind. Regular exercise, adequate sleep, and healthy eating habits lead to both physical and mental health.

6. Express gratitude, whenever possible. We too often take our lives for granted. Learn to appreciate and savor the wonderful things in life, from people to food, from nature to a smile.