In one study, they just measured people's positivity in general—are you a positive person or not so much? And then they shot people's nostrils up with rhinoviruses. Rhinoviruses are the viruses that cause the common cold ... Three times the number of people get sick in the, kind of, not-so-positive mood category as in the positive mood category.

One of the big things that affects happiness is social connection ... Every available study of happy people suggests that happy people are more social; they spend more time, like just physically spend more time, around other people, and then they tend to prioritize time with their friends and family members.

There's one study that suggested a half-hour of regular cardio exercise every day can be as effective as a prescription of Zoloft for improving your mental health.

One famous study had subjects get normal sleep for two days, then deprived sleep for a week (deprived wasn't zero hours of hours of sleep, it was five hours of sleep), and then you go back to normal sleep. And what you find is that, during that week of deprived sleep, subjects' mental health tanks—almost to the point that it looks like their mood levels had hit clinical depression.

Research shows that if you just engage in practices of gratitude, just the simple act of, at night, scribbling down 3-5 things that you're grateful for, research shows that that can start significantly boosting your well-being in as little as 2 weeks.

I think one thing you can do to make your kids ultimately happier and definitely to make them psychologically healthier is to let them be unhappy. It is to let them fail; it is to let them screw up; it is to let them cry; it's to let them see you do the same things because that is the way by which they do stuff.

The stuff that we know is good for physical health, like making sure you're getting enough sleep, making sure you're getting enough exercise, making sure you're eating right, those physical things seem to have a huge impact on people's mental health—much more than we think.

There's evidence suggesting that a half hour of cardio every day is as effective as a prescription of Zoloft for reducing depression symptoms.

There's so many surprising benefits of fun—it reduces your inflammation, it improves your heart condition, it can improve your relationships. It actually stimulates brain growth. This is why very young kids play a lot and baby animals play all the time, because play and doing fun things can actually increase brain growth. But it also has a surprising effect on your productivity.

If you self-report being time-famished, that's as big a hit on your well-being as if you self-report being unemployed. We know unemployment's awful for your happiness; just feeling like you don't have any time is bad, too.

I think the fastest thing you can do to improve your happiness is to get in a little social connection. Even really simple studies show if you chat with the barista at the coffee shop, if you talk to somebody on your commute, those quick moments of social connection, even with a stranger, can boost your positive mood.

This is a bias that researchers call the arrival fallacy... 'When this happens, I'll be happy.' And, you know, it's not like we're mis-predicting—you get a new house and like, yeah, that feels good, but it doesn't feel as good as you're going to think, and it doesn't feel good for as long as you're going to think.

Happy people tend to be more grateful, and grateful people tend to be happier. Happy people tend to spontaneously count their blessings. They tend to spontaneously notice all the good things, not the bad things in life.

One of my favorite famous studies on social comparison actually looked at Olympic athletes and Olympic medal winners. And what they did was they looked at who's the happiest on the Olympic medal stand. And what they find, which is surprising, is the person who wins the bronze is actually much, much happier than the person who wins the silver.

Social relationships and strong social relationships are necessary for happiness. They're not sufficient for happiness, but you can't find happy people that don't have them.

There's also evidence that exercise can have a long-standing effect on your well-being. So, you do, say, a half-hour of cardio Monday morning, the data suggests that little bump in endorphins... that will still be there with you, if you do it Monday at 9 AM, until around Tuesday at, like, 1 PM.

When I list out tips for how to feel happier, often the first one is improve your social connection. Every available study of happy people suggests that happy people are more social.

There's some work by Liz Dunn and her colleagues that shows that spending money on yourself actually makes you less happy than spending money on other people.

There's evidence that in as little as 2 weeks, the simple act of writing 3-5 things you're grateful for down on a piece of paper can improve your well-being, like significantly improve your well-being.

There is lots of evidence that doing for other people can make us happy, but that's only if we have the bandwidth to do for other people. And the problem is that we sometimes don't.

Being religious, it turns out, is actually pretty good for your happiness—or at least, I should clarify, not necessarily... believing in religious doctrine but actually taking part in religious practices...

It turns out that the simple act of scribbling down 3-5 things you're grateful for at the end of the day can significantly improve your well-being in as little as two weeks.

There is some part of happiness that's heritable. So, if you came from parents who were super happy and grandparents who are super happy, you're more likely to be a little bit happier. But it's not as heritable as most traits. It's probably less heritable than something like your height or even your weight.

I think of being happy in your life as having a decent ratio of positive to negative emotions. It's not no negative emotions; it's not positive emotion, you know, happiness emoji all the time. But it's, like, generally having a decent ratio of things like laughter and joy to things like sadness, anger, and so on. That's happy in your life.

If you look at those spiking rates of depression and anxiety, the kink in the curve of these things going up seems to happen around the same time that the iPhone was introduced and started to go viral.

We don't tend to think of the good things in our lives objectively ... Our brain just can't hold onto things objectively. Our brain has to use what's called a reference point. Who can I compare myself to and see how I'm doing—with my income, with my looks, or, in this case, with my performance in the Olympics?

Emotions are signals, and overwhelm is a good signal of 'this means you got to step back; you gotta start saying no to some of these obligations.

There's this, kind of, mistaken notion that happiness is all about self-care and self, self, self ... But what the science suggests is that happy people are really other-oriented.

I feel like we could solve most of the mental health crisis on college campuses if we just got these kids to sleep.

One of the key ingredients for happiness that we often forget is what's known as time affluence—this subjective sense that we have some free time.

There is definitely a genetic component to happiness, but it's much smaller than we think. In terms of what's called heritability.... it seems like heritability is around 40% for happiness.

If you look at the positive psychology literature, one of the hugest effects on our own happiness is our social connection.

A full, happy life... actually comes with some negative emotions. They can teach us things. Many of our negative emotions are really problem-solving emotions. When you get sad, it's not just something your body does to torture you; it's often telling you you're missing something in your life ... Maybe missing a person in your life or you're not happy with your job, and maybe you should do something to change it.

The simple, fleeting connections that we have with strangers can be really powerful for our well-being ... It really seems to bump up our positive emotions.

We really have to make sure we're protecting our physical health because that has a huge implication on our mental health.

Grateful people are more likely to do nice stuff for other people .... It also makes you a more productive person because one of the people gratitude makes you want to give back to is your future self. So, it turns out grateful people are more likely to eat healthier; they're more likely to save more for retirement, easily; they're more likely to exercise.

What I worry about a lot is that parents who, kind of, in this very well-intentioned way, try to solve problems for kids take away the opportunity that kids get from solving those problems themselves. And that might not seem bad, except that there's lots of evidence that that contributes to kids' beliefs about whether they can solve those problems themselves.

This is our bias of affective forecasting ... We get wrong, not the direction—we kind of know good things are going to make us feel good—but we definitely get wrong the intensity and the duration that that boost in happiness is going to last.

You need to find ways to kind of say 'no' to give yourself the bandwidth; boundaries are healthy ... Make sure when you're saying 'yes' that it really is a real yes.