The author of groundbreaking books including the best-selling Women’s Bodies, Women’s Wisdom, and The Wisdom of Menopause, Dr. Christiane Northrup spent decades as a physician in the field of obstetrics and gynecology before her writing on women’s health made her one of the country’s leading voices on how women can empower themselves to take charge of their own bodies—and happiness.Releasing her first book for children, "Beautiful Girl," earlier this year, Dr. Northrup has also written and spoken candidly on her own journey through motherhood, divorce, and menopause and on how she has pursued and found joy through passions like the Argentine tango.She spoke with S&H editor in chief Karen Bouris.I see a lot of women in their 70s and 80s dealing with depression as they get older. Where does that come from?First, let me just say that what I’ve witnessed in my own mother is exactly the opposite. She’s 87, and her best friend is 90. And they are having the time of their lives—planning to drive my mom’s RV to Alaska this summer. This is possible because neither is afraid of death, and both know how …