Positive psychology researcher Shawn Achor says a daily gratitude circle cultivates happiness. Photo credit: Sam Edwards/Getty Images.

The holiday season is a good time to count your blessings and give thanks for what you have, says positive psychology guru and Yale University researcher Shawn Achor.

"The power of gratitude is not only one of the fastest ways to raise the level of happiness, it literally transforms your health," said Achor.

There's some science to back up that statement. In a trio of experimental comparisons done at the University of California, Davis, those who kept weekly gratitude journals reported feeling better about life, exercised more regularly and slept more soundly compared with those who wrote down their daily hassles or reflected on the neutral events in their lives.

Of course, it can be hard to find a moment to slow down and reflect on all the positive things in your life. But ever the optimist, Achor says anyone can cultivate an attitude of gratitude by focusing on it for just a few minutes each day.

Here, he offers four ways to do just that:

• Retrain Your Brain. While your brain receives more than 11 million bits of information per second, Achor said that it can process only about 40. Therefore, it takes practice to scan for the positive while screening out the negative. If you keep at it, Achor said you can turn your brain into an optimism machine, even if you're grouchy by nature. "It doesn't matter what you're grateful for," Achor said. "What matters is that you are training your brain to view the world differently."

• Pass It along. Gratitude has a ripple effect, Achor said. That means parents can pass it along to their children. Achor recommends holding a daily family gratitude circle in which every member of the family describes three things they are grateful for that day.

• Email Your Thanks. Once a day, take two minutes and write an email to someone expressing your gratitude for something he or she did. Achor said you'll be surprised how good this simple act will make you feel. It's also a great way to foster a stronger social network.

• Bless Your Stress. Find something positive to focus on in the face of adversity, Achor advised. As a University of Connecticut study found, a grateful heart is a healthier heart. In this investigation, patients who viewed their first heart attack as a blessing in disguise for giving them a new appreciation for life were less likely to have a second attack than those who blamed their heart troubles on others.