If you believe your happiness hinges on landing a better job, or that you're doomed to inherit your mom's pessimistic disposition, here's some amazing secrets to happiness you should know:

Genetics determines only 50 percent of happiness, while a mere 10 percent is influenced by life circumstances (such as your financial situation, health or marriage). This leaves a surprising 40 percent of our capacity for happiness within our power to change, according to Sonja Lyubomirsky, Ph.D., social psychology at the University of California and author of The How Of Happiness, who has arrived at this scientific formula of happiness after almost 20 years of research.

In other words, you can choose to be happy. Check out these strategies to take your happiness into your own hands:

Learn to be grateful

"One way to practice this strategy is with a "gratitude journal" in which you write down the 3 to 5 things for which you are currently thankful," suggests Lyubomirsky. It can be something mundane, to the bigger blessings in your life -- whether it's that your partner helped out with the housework, or that your baby's taken her first steps. Whenever possible, express your appreciation to the person you're thankful for -- the gesture will make you both feel happier.

Practice little acts of kindness

Give up your seat to an elderly passenger on the bus, or offer to help a coworker with computer problems. Being kind to others, whether friends or strangers, triggers a multitude of positive effects, explains Lyubomirsky. It makes you feel compassionate and connected to others, as well as more optimistic and confident. Plus when you commit acts of kindness, they earn you smiles and reciprocated kindness.

Set meaningful goals

People who strive for something significant are happier than those who don't have strong aspirations, says Lyubomirsky. So pursue a goal that you value, whether it's learning a new language or taking up a fitness class.

Take care of your body

Getting enough sleep, exercising, meditating, and smiling can all boost your mood and promote energy.