What Makes Life Meaningful? Views from 17 Advanced Economies (opens in new tab)

It's also worth looking at the 75-year Grant Study https://en.wikipedia.org/wiki/Grant_Study

From Wikipedia:

Main results

George Vaillant, who directed the study for more than three decades, has published[8] a summation of the key insights the study has yielded:

    Alcoholism is a disorder of great destructive power.
        Alcoholism was the main cause of divorce between the Grant Study men and their wives.
        Strongly correlates with neurosis and depression, which tended to follow alcohol abuse, rather than precede it.
        Together with associated cigarette smoking, was the single greatest contributor to their early morbidity and death.
    Financial success depends on warmth of relationships and, above a certain level, not on intelligence.
        Those who scored highest on measurements of "warm relationships" earned an average of $141,000 a year more at their peak salaries (usually between ages 55 and 60).
        No significant difference in maximum income earned by men with IQs in the 110–115 range and men with IQs higher than 150.
    Political mindedness correlates with intimacy: Aging liberals have more sex.
        The most-conservative men ceased sexual relations at an average age of 68.
        The most-liberal men had active sex lives into their 80s.
    The warmth of childhood relationship with mothers matters long into adulthood:
        Men who had "warm" childhood relationships with their mothers earned an average of $87,000 more a year than men whose mothers were uncaring.
        Men who had poor childhood relationships with their mothers were much more likely to develop dementia when old.
        Late in their professional lives, the men's boyhood relationships with their mothers—but not with their fathers—were associated with effectiveness at work.
        The warmth of childhood relationships with mothers had no significant bearing on "life satisfaction" at 75.
    The warmth of childhood relationship with fathers correlated with:
        Lower rates of adult anxiety.
        Greater enjoyment of vacations.
        Increased "life satisfaction" at age 75.

George Vaillant's main conclusion is that "warmth of relationships throughout life has the greatest positive impact on 'life satisfaction'". Put differently, Vaillant says the study shows: "Happiness is love. Full stop."[9] In response to accusations that the statement was sentimental or overly general, Vaillant revisited his findings and concluded: "The short answer is L-O-V-E."[10] The CBC reported that the "[Grant] study proves Beatles right: All You Need is Love."[10]