Here’s the first study on gratitude Emmons conducted with his team: Researchers split participants into three groups. Every week the participants kept a journal where they described, in a single sentence, five things they were either grateful for (the gratitude...

“So gratitude is a key to happiness, as I will argue from a scientific angle. And happiness itself is a good thing. An implicit assumption that many of us hold is that happiness depends on happenings—by what happens in our...

“Recent research suggests that optimal mental health is associated with high ratios of positive to negative emotions. According to this model, normal functioning is characterized by ratios near 2.5 (that is, 2.5 times more positivity than negativity), whereas optimal functioning...