When you're in a funk, there's nothing more annoying than those people who tell you to just smile your way out of it. But it turns out, they may be onto something. Scientists from Wake Forest University found that people who were asked to do something bold and energetic -- like participate in a group conversation -- ended up feeling happier than those who kept mum. In other words, with a little bit of effort, you can turn your own frown upside down. We asked Sonja Lyubomirsky, author of The How of Happiness, for three easy ways to make a lasting change in your mood:

1 Practice acts of kindness Lyubomirsky discovered that people who did five small good deeds one day of the week were happier than those who stretched the same number of kind acts over seven days. One day of small gestures, such as letting a car ahead in traffic or opening a door for a stranger, can add up to lots of grins all around.
2 Remember the good things Once a week, make a quick list of things you're grateful to have -- good health, an amazing BFF, even a great head of hair. Or try writing a letter to someone who had a positive impact on your life. Lyubomirsky's research showed that spending as little as eight minutes a week penning a thank-you -- even without sending it -- lifted people's spirits.
3 Predict the future Every week, imagine your life several years down the road, and then make a diary entry that focuses on how well things have worked out. Did you complete your first 5K run, successfully navigate your kids' tough tween years, or land that promotion you always wanted? Visualizing a happy, satisfying future can help give you an optimistic feeling for the present, says Lyubomirsky.