Megan Novotney was shocked to be pregnant six months after giving birth to triplets.
The Chicago-area stay-at-home mother had a choice: She could wallow in the fact that her life had become an endless cycle of diapers and bottles, or she could do something to try to make herself a little happier.
Novotney chose happiness, and this fall, when her children were 3 and 2, she enrolled in a yoga teacher training program.
"You lose yourself as a person once they arrive," Novotney said. "Now, I'm able to put myself first, and it makes me a better mom, and better teacher, a better wife. When the plane is going down, you put your own mask on first."
You can choose to be happy or you can choose to be unhappy — and that choice is up to you, said Gretchen Rubin, author of "Better Than Before" and "Happier at Home," and host of the podcast "Happier with Gretchen Rubin."
About 50 percent of happiness is genetically determined, so some people will naturally be happier than others, Rubin said. The next 10 to 20 percent of happiness results from life circumstances: age, marital status, income and education, Rubin said, estimating her percentages based on multiple studies by University of California researchers. That remaining 30 to 40 percent? It's all you.
She said we each have a range set, from one to 10, with 10 being the happiest.
"You might be four to seven, and someone else might be seven to 10," Rubin said. "Even when they're blue, they might not be so blue, but you can always be lifted to the top of your range."
The trick is to know how to get there. If you don't know how to be happy and you're not a naturally happy person, you may be stuck at four, and that's just depressing.
For example, many people incorrectly believe that shopping is the key to their happiness, said Karl Moore, author of five books including "The 18 Rules of Happiness."
"It provides the temporary high," Moore said, "and once we're used to the new level of happiness that comes with the acquisition, it becomes the norm."
Others assume that having children will make them happier, and this also isn't true, said Ruut Veenhoven, professor of social conditions for human happiness at Erasmus University Rotterdam in the Netherlands.
"Marriage becomes less romantic and life choices more constrained, and these negatives tend to outweigh the evident positives of having children," Veenhoven said. "The reason that most parents had expected otherwise is colored information, both in the media and from their mothers, who are eager to become grandmothers and have forgotten their perils of the past."
Even winning the lottery or increasing your income doesn't necessarily equate to happiness, Veenhoven said. Once income rises above $75,000, life satisfaction doesn't increase, according to a study by Princeton University researchers. It goes back to the retail theory: that you become accustomed to whatever you purchase but also because you have to log many hours at work making that money, which makes people unhappy.
But there are other easy ways to become happy quickly, and these don't cost anything, Rubin said.
Going outside is an easy fix, she said.
"There's light even on the cloudiest day, and it lifts your mood," Rubin said.
A University of Michigan study showed that strolling through nature can lower stress, and can even be a nonpharmacological approach to depression. If you're stuck at your desk, you can simulate the outdoor effect by simply looking at a picture of a nature landscape, according to a study published in the Korean Journal of Radiology. Researchers found that those who looked at green landscapes had heightened activities connected with positive memories, compared with those who viewed urban photos.
Hanging out with cheerful people can also do the trick.
Happiness is a feeling, and it's contagious — so if you're around people who are happy, you'll probably be in a good mood. Unfortunately, the flip side is also true, Rubin said.
A study published in the Proceedings of the Royal Society found that each happy friend increases your chances of happiness by 11 percent, although each unhappy friend doubles your chances of being unhappy.
"We're constantly passing emotions back and forth to each other," Rubin said. "If they're happier, they will help lift you up — it won't take you all the way, but it will tend to pull you that way."
But you can surround yourself with miserable people and still remain positive because you're the only person in charge of your own emotions, said Moore, who believes that these contagious feelings can be quashed.
"Only you can determine your state of mind," he said.
One way to adjust your state of mind is to stop feeling sorry for yourself, Moore said.
"That's a massive block to people's happiness," he said. "Self-pity eats up everything around you, and it leaves you feeling bitter and twisted."
If you want to truly experience happiness, Moore said, you simply need to let go of your self-pity, and start feeling grateful for what you do have, whether it's a warm home, a cup of tea or a free country.
"You will naturally propel your happiness," he said.
In Novotney's case, she stopped feeling sorry about being stuck at home with four babies living off of one income. Instead, she focused on reasons to be grateful, such as being able to home-school the children.
And once she began taking care of herself through practicing yoga, she found an instant morale boost.
Saying "yes" to classes or other experiences is an easy way to increase your spirits.
A study from San Francisco State University found that experiences — rather than material items — make people happy because the memories from those experiences and adventures can last for a very long time.
The experiences don't need to be lavish, and they don't even need to take you out of your home.
Anything that deepens an existing relationship or broadens one has been shown to make you happier, Rubin said.
So reconnecting with old friends, starting a book club, going to a reunion, throwing a party or meeting someone for coffee will make you happy.
"Even fleeting connections with people boost the mood," Rubin said. "Go talk to someone face to face instead of sending an email."
And remember that life is fleeting, so you should take advantage of every moment.
"Learn to understand that life is only ever for now," Moore said. "Even this shall pass."
Danielle Braff is a freelancer.