We search for meaning at the start of each chronological decade.

Recent soulful introspection by my husband, who moves from age 59 to 60 in late December, motivates me to point to this study by Alter and Hershfield, who perform six cross cultural studies to show the same thing I recall from my own experience when I was 49, 59 and 69: that people renew their search for meaning as they face a new decade. The studies aggregated data available on several major survey data websites relevant to values, search for meaning, extramarital affairs, suicide rates, and marathon sign-ups and performance. The summary from their significance and abstract sections:

...people audit the meaningfulness of their lives as they approach a new decade in chronological age, further suggesting that people across dozens of countries and cultures are prone to making significant decisions as they approach each new decade...Six studies show that adults undertake a search for existential meaning when they approach a new decade in age (e.g., at ages 29, 39, 49, etc.) or imagine entering a new epoch, which leads them to behave in ways that suggest an ongoing or failed search for meaning (e.g., by exercising more vigorously, seeking extramarital affairs, or choosing to end their lives).