In positive psychology research, gratitude is strongly and consistently associated with greater happiness. Gratitude helps people feel more positive emotions, relish good experiences, improve their health, deal with adversity, and build strong relationships.

One group wrote about things they were grateful for that had occurred during the week. A second group wrote about daily irritations or things that had displeased them, and the third wrote about events that had affected them (with no emphasis on them being positive or negative). After 10 weeks, those who wrote about gratitude were more optimistic and felt better about their lives. Surprisingly, they also exercised more and had fewer visits to physicians than those who focused on sources of aggravation.

https://www.health.harvard.edu/healthbeat/giving-thanks-can-make-you-happier