What is the key to happiness? We look at the science behind it.

young child sits at a dining table surrounded by adults who laugh and clap for her as she blows out birthday candles on a cake.
(Image credit: Getty Images)

Is there a key to happiness? It's among humanity's biggest questions and one that we still don't fully know the answer to. While scientists are getting closer to pinpointing certain factors that may increase happiness, there are several reasons why finding a universal formula isn't straightforward. 

Happiness is a complex phenomenon that is difficult to define and measure in an objective way. Sam Jahara, a psychotherapist at Brighton and Hove Psychotherapy in the U.K., told Live Science that happiness is usually linked to feelings of joy, ease and gratitude. Happy people often have a positive outlook on their life, both past and present and despite negative circumstances, and they look forward to the future, she said. 

But happiness is not the same as life satisfaction, said Dr Maurice Duffy, a mindset coach and visiting professor of innovation and entrepreneurship at the University of Sunderland in the U.K.

"When we are describing happiness, we are saying that our mental state is happy," he told Live Science. "When we are describing life satisfaction, we are making a value judgment over something in our control and whether we perceive it benefits or harms us, or makes us better or worse off."

Understanding the science behind happiness is also challenging because the meaning and importance of happiness varies between different cultures, according to a 2016 review published in the journal Current Opinion in Psychology. Americans tend to define happiness in terms of pleasure and view happiness as a universally positive thing, whereas East Asian and Middle Eastern cultures can see happiness as socially disruptive and are more ambivalent about whether it is a good thing, the review suggests.

The way happiness is measured — mostly using questionnaires and happiness scales — is not precise enough to draw firm conclusions on the formula for happiness either, a 2021 review published in the journal Synthese noted.

But despite these challenges, research into happiness suggests there are some common themes, suggesting the key to happiness may still be within science’s reach.


There is growing evidence that physical activity may be central to happiness across a person's lifespan. A 2020 study published in the International Journal of Environmental Research and Public Health measured physical activity and happiness in 2,345 young, middle-aged and older adults. Individuals with high and moderate activity levels reported significantly higher happiness levels than inactive participants, regardless of their age group. 

But physical activities that affect happiness can include more than just exercise, a 2017 study published in the journal PLoS One found. In the study, over 10,000 participants tracked their happiness and physical activity levels in a smartphone app, which gathered information about their movements from an accelerometer. The results showed that individuals who were more physically active — whether this was exercise or non-exercise activity — had higher self-reported mood scores. Examples of non-exercise activity include walking to work, mowing the lawn or gardening.

Three women stretching before exercising outdoors

(Image credit: Catherine Falls Commercial via Getty Images)

Dr. Ioannis Liakas, a fellow of the Royal College of Physicians and honorary senior lecturer at Queen Mary Medical School in the U.K., told Live Science that there are several reasons why physical activity can increase happiness. 

"Exercise is good for our bodies, but it can also boost your mood and help you deal with depression and anxiety," he said. "Being active releases chemicals in your brain [including serotonin and endorphins] that make you feel good — boosting your self-esteem and helping you concentrate, as well as sleep well and feel better." 

Social connections

A 2018 review published in the journal Nature Human Behaviour suggests that the relationships we have with other people — our social connections — may be crucial to our sense of happiness. This is because good relationships with others give us a sense of belonging, meaning, purpose and acceptance, Jahara said.

"Humans are relational beings," she said. "Through others we feel seen, heard and validated. In turn, giving to others brings us a sense of satisfaction and fulfillment, and makes us happy as well. Without good relationships we invariably feel lonely and isolated which leads to poor mental health." 

Performing acts of kindness towards others may particularly enhance people's happiness levels, according to a 2018 meta-analysis published in the Journal of Experimental Social Psychology, while a 2019 study published in The Journal of Social Psychology found that the more kind acts a person performs (defined as actions intended to benefit others, such as volunteering at a charity or helping a lost stranger get to their destination), the happier the person tends to be. It takes seven consecutive days of kindness activities to positively affect happiness levels, the study found.

couple laughing together at a table

(Image credit: Getty Images)

Psychological wellbeing

A person’s ability to maintain a state of happiness also depends on how they deal with stress and adversity, Jahara said. People who practice self-compassion (a positive and caring attitude towards themselves in the face of failures and individual shortcomings) and gratitude (a state of thankfulness) may be happier, she said.

"Self-compassion and gratitude are ways of cultivating a positive view of self, others and the world around us," Jahara said. "Our negative bias can lead us to developing self-defeating thoughts and a bleak view of the world. This then becomes our reality as we constantly search for things to confirm this view."

Instead, taking a balanced view and understanding that things are mostly neither always good nor always bad can be important for happiness, Jahara said. 

"The ability to hold a balanced perspective on life and hold both positions at the same time is what defines a healthy mind," she said. "Therefore, cultivating a positive thinking loop, rather than a negative one, will impact our ability to feel happy."

Digital media

How we use digital media may also be an important factor in happiness, Duffy said, with smartphones and social media being a double-edged sword.

"There are a number of links between digital media use and happiness," he said. "One centers around the social connection it enables — which can be positive or negative — and in turn affects our levels of happiness accordingly."

According to a 2019 meta-analysis published in the Journal of Computer-Mediated Communication, digital media that focuses on direct interaction between users, such as phone calls and texting, may enhance happiness the most. Social media can both increase or decrease happiness, the researchers noted, and the effect may depend on how a person uses them. Interaction, self-presentation and entertainment were linked to better wellbeing, whereas passive content consumption (without interacting with other users) was linked to poorer wellbeing. 

Man at wooden desk with tablet, laptop and smartphone

(Image credit: JKstock via Shutterstock)


Whether or not money can buy happiness may depend on what — or who — the money is spent on, according to a 2016 review published in the journal Current Opinion in Psychology. Spending money on oneself does not tend to make people happy, the researchers suggested, but people can feel happiness from spending money on others, as well as from acquiring experiences instead of possessions. 

A 2010 review published in the journal International Review of Economics also found that leisure may be the only component of consumption that can increase happiness. Spending money on activities like hiking, books or traveling may be more important to happiness levels than buying a house or a car, the researchers found. 


Spending time in nature may also increase feelings of happiness, Duffy said. 

"The research suggests that 'nature connectedness' [the subjective sense of connection people have with the natural environment] has a distinct happiness benefit," he said. 

According to a 2014 meta-analysis published in the journal Frontiers in Psychology, there is a "small but significant" link between nature connectedness and happiness. In terms of measures, associations were strongest between happiness and "inclusion of nature in self" — a measure of one's feeling of connection to the natural environment and the belief that the environment is an important part of one's self-concept.

Being in nature can also have a beneficial effect on mental health, Liakas told Live Science. 

"Nature can help us feel happier, feel our lives are more worthwhile and reduce our levels of depression and stress," he said. 

Is happiness a choice?

If happiness is a state of mind, as Duffy suggested, can someone choose to be happy? Research suggests that happiness can be cultivated through conscious life choices in areas such as relationships, exercise and surroundings. However, a person's happiness may depend on their ability to make those choices, especially considering financial barriers and mental health. 

Perhaps the first step to feeling happy may be to get better at feeling in general, Jahara said.

"This means appropriate emotional responses to different situations," she said. "There are different ways of developing emotional literacy, psychotherapy being just one example. Therefore, we could say that there is a choice in improving one's ability to feel happiness, as well as others feelings too."

Anna Gora
Health Writer

Anna Gora is a health writer at Live Science, having previously worked across Coach, Fit&Well, T3, TechRadar and Tom's Guide. She is a certified personal trainer, nutritionist and health coach with nearly 10 years of professional experience. Anna holds a Bachelor's degree in Nutrition from the Warsaw University of Life Sciences, a Master’s degree in Nutrition, Physical Activity & Public Health from the University of Bristol, as well as various health coaching certificates. She is passionate about empowering people to live a healthy lifestyle and promoting the benefits of a plant-based diet.