The “positive psychology” movement, championed by Martin Seligman in the 1990s, has led the field of gerontology into a movement that author Robert Hill calls positive aging. Hill adopts the perspective that “happiness does not just happen.” It is our actions and our intentional behaviors that affect the quality of our lives. In his 2005 book Positive Aging, he lists some of the key ingredients of successful or positive aging: taking control of our lives, being active in our communities, being engaged with others, building close relationships, and seeking meaning and purpose. He writes, “At the individual level, it is about individual traits: the capacity for love and vocation, courage, interpersonal skill, aesthetic sensibility, perseverance, forgiveness, originality, future mindedness, spirituality, high talent and wisdom.”

A recent article in the Atlantic on the seminal work of Dr. George Vaillant at Harvard—titled “What Makes Us Happy?”—reported on the famous 72-year study of 268 men who entered Harvard College in 1937. This important study, although conducted on the lives of relatively privileged men, has reinforced many other researchers’ conclusions that (1) close, long-lasting, and meaningful relationships are key to positive aging, happiness, and a sense of well-being in our later years, and (2) engagement in purposeful activities that have meaning to us are essential to positive aging and the sense of a life well lived. As Vaillant summarizes: “Enjoy where you are now. Play, work, and love. Happiness is love!”

My own studies on adult women’s development are consistent with these findings, but they also reveal women’s more holistic and cyclical life patterns. Since we are living longer and healthier lives, we must now find and use new developmental models in order to reinvent that lengthening period of our later lives, over age 60, that I call “the third third” of life. Although the three thirds of life are essentially equal in length, many of us will live beyond age 90, making the third third of life potentially our longest period.

We always think that the stage of life we are currently in is the most significant. Just think about the self-centered teenager or the 30-year-old Hollywood celebrity or the 45-year-old working mother of three who thinks that the whole world is involved in her exhausting daily juggling act.