UC Davis psychology professor Robert Emmons has made a science out of thanksgiving. In the past decade, his research has shown that people who count their blessings -- not just on the fourth Thursday of November each year, but in daily gratitude journals -- exercise more regularly, complain of fewer illness symptoms and feel better about their lives overall.

Compared with those who chronicle daily hassles, people who take time instead to record their reasons for giving thanks also feel more loving, forgiving, joyful, enthusiastic and optimistic about their futures. Their family and friends report that they seem happier and are more pleasant to be around.

"Gratitude is literally one of the few things that can measurably change people's lives," Emmons says.

He is the author of three books about gratitude. The most recent, "Thanks! How the New Science of Gratitude Can Make You Happier," was published earlier this year. It outlines 10 research-based strategies for cultivating a feeling of thanksgiving throughout the year, including keeping a daily gratitude journal.

Emmons said anyone can cultivate a more grateful approach to life, but he warns that the effort is not for the "intellectually lethargic."

"Far from being a warm, fuzzy sentiment, gratitude is morally and intellectually demanding," he says. "It requires contemplation, reflection and discipline. It can be hard and painful work."