The Harvard Study of Adult Development might be the most comprehensive study ever conducted. The study started in 1938, included three generations, and analyzed more than 2000 people over 85 years.
The study discovered two major factors that most correlated with well-being and happiness:
Taking care of their health
Building loving relationships with others turned out to be the most significant predictor of health and happiness during aging.
For the complete article: (Medscape, July 12, 2023)