At the end of the day, don’t we all want to be happy? Here are 5 ways to get there

(CNN) — Americans are really into pursuing happiness.

What happiness means is different for each individual and may shift over a lifetime: joy, love, purpose, money, health, freedom, gratitude, friendship, romance, fulfilling work? All of the above? Something else entirely? Many have even suggested that while we may think we know what will make us happy, we are often wrong.

One man may have cracked the code for what makes a happy and healthier life — and he has the data to back him up.

Dr. Robert Waldinger is the director of the Harvard Study of Adult Development — possibly the longest-running longitudinal study on human happiness, which started back in 1938. (The original study followed two groups of males, Harvard College students and adolescents in Boston’s inner city. It was expanded in recent decades to include women and people of more diverse backgrounds.)

Plenty of components are at play in the quest for a happier life, but the key comes down to one main factor: quality relationships.

“What we found was that the important thing was to stay actively connected to at least a few people, because we all need a sense of connection to somebody as we go through life,” Waldinger told CNN Chief Medical Correspondent Dr. Sanjay Gupta recently on his podcast Chasing Life.

“And the people who were connected to other people lived longer and stayed physically healthier than the people who were more isolated,” he said. “That was the surprise in our study: not that people were happier but that they lived longer.”

Waldinger, who shares many of the study’s lessons in the book he coauthored, “The Good Life: Lessons From the World’s Longest Scientific Study of Happiness,” is a psychiatrist, a professor of psychiatryat Harvard Medical School and a Zen priest.

You can listen to the full episode of the podcast here.

Why would having quality relationships help people live happier and longer lives?

“The best data that we have, and other studies have, has to do with stress and relief of stress,” Waldinger said. “If I have something upsetting happen today, I can literally feel my body rev up into fight-or-flight mode. ... That’s not a problem, that’s normal, the fight-or-flight response. But what we’re meant to do is go back to equilibrium when the stress is removed. And if I can go home and complain to my wife or call up a friend, I can literally feel my body calm down.”

He said neuroscience research suggests that people who are isolated or feel lonely stay in a low-level, fight-or-flight mode, which means they have higher levels of circulating stress hormones. “They have immune systems that don’t function as well, so they get infections more easily,” he said. “And that chronic inflammation breaks down body systems.”

Additionally, people who are isolated don’t have anyone looking out for them, Waldinger said, ensuring they eat well, visit the doctor and engage in other behaviors that lead to better health.

It doesn’t meanintroverts or people without partners are doomed to short, miserable lives. Having one or two good friends — someone you can count on — is enough, he added.

What can you do to live your happiest life? Waldinger has these five tips.

Don’t neglect the basics

Optimize your physical health. “On the one hand it sounds obvious, but we find that the people in our study who took care of their health lived longer and had more years when they were free of illness as they got older,” Waldinger said.

“It means, exercising regularly. It means eating well. It means not becoming obese. It means not abusing alcohol or drugs. It means getting a reasonable amount of sleep,” he said. “Those things matter a lot.”

If you don’t know where to start, sign up for these newsletters on exercise, eating right and sleep.

Invest in your personal relationships.

“Take care of your social fitness, if you will,” Waldinger said. “If you feel that you need more connection with people, be active in working on that.”

Improving your social fitness can be done in two different ways.

The first is quantity.

“If you feel you don’t have enough people in your life to whom you’re connected,” Waldinger said, “you can take active steps to make more relationships, to bring more people in your life.”

Get involved in activities you enjoy alongside others. “It could be volunteering for a community activity that you enjoy or care about. ... It could be joining a club. It could be being involved in a religious community,” he said. “If you go to the same group of people again and again, you’re likely to strike up conversations around the thing that you all care about and that you’re there to do.”

Doing so, he said, is an easy way to introduce new people into your life.

Strengthen existing relationships

The second way to improve your social fitness is quality.

“What if I have enough people in my life, but I don’t feel connected enough to them; I have let my friendships go,” Waldinger said. “What we find in our study is that people who take small actions, day-to-day, to stay in touch and to connect with people are the people who keep their relationships strong.”

This effort doesn’t necessarily require heavy lifting. It means taking small but consistent actions.

“It means you could just make it a point on your commute to work every day to call somebody or to text or email somebody, just to stay in touch with a friend,” he said. “It means actively reaching out to go take a walk together or have coffee or have a meal together.”

These small but regular actions will keep the relationships you care about more active and more vibrant, he said, “rather than letting them wither away from neglect.”

Express yourself

Another tip, Waldinger said, is to consider the values that are most important to you and express them.

“It might be that what you value the most is authenticity — and so, think about where do I get to express that in my life and are there ways I can do more of that?” he said. “Maybe you value family.”

To home in on self-expression, he said to think about the core values that you couldn’t imagine your life without and then think about where in your life you can express those and how you can do more of that in your life. “Because the people whose activities allow them to express what’s most meaningful to them,” he said, “those are the people who end up being the happiest and feeling the best about their lives.”

Accept and embrace change

People change all the time, and it means relationships are changing, too; you need to learn to accommodate these changes.

“The question is, can we notice how we’re changing (and) how the other person is changing and accept that change and maybe even celebrate and support that change rather than resisting it,” Waldinger said. “Often relationships get into trouble when we try to freeze them in some way or freeze the other person.”

One way to learn to accept such changes, particularly when someone’s annoying or when you’re having trouble in a relationship, Waldinger said, is to bring as much curiosity as you can to the relationship.

“First of all, it helps the other person feel that you’re interested, that you genuinely want to know,” he said. “It also allows you to learn more about why are they thinking the way they are? And that’s particularly important now where we’re so divided from each other.”

We hope these five tips help put you on a path to what you consider to be a good, happy life.

And remember: No life is happy all the time. “Moment to moment happiness changes,” Waldinger said. “We can imagine that ‘I just have to do everything right, and then I’ll be happy all the time’ — and that’s not true for anybody.”

Listen to the full episode here. And join us next week on the Chasing Life podcast when we turn the spotlight on the safety of sunscreens.

CNN Audio’s Eryn Mathewson contributed to this report.

Having quality relationships can contribute to a happier and longer life, as Dr. Robert Waldinger from the Harvard Study of Adult Development found. This is because people who are connected to others experience lower stress levels and improved immune systems, leading to fewer infections and chronic illnesses. Furthermore, people with strong relationships are more likely to have someone looking out for their health, encouraging them to exercise, eat well, and visit the doctor. It's not necessary to have a large number of relationships; having a few close friends is enough to reap these benefits.