Making the next decades the best years of your life.

It starts when we’re 35. For many women within five years of their fortieth birthday, their biggest worry isn’t their relationship (or lack of one), their boss, their kids, their financial situation or even their health. It’s the calendar.

We can’t deny the fact that we age. No matter how hard we try to remain youthful, we are getting older. Aging is simply part of the natural and beautiful cycle of life, as sure as the seasons changing. Yet few events, it seems, are as unnerving to women as thinking about that fortieth candle on the birthday cake.

I first began to observe this phenomenon several years ago among the 30- to 50-year-old clientele who frequented my Manhattan therapy practice. They had a single common obsession: “I don’t want to turn 40.” The “big four-oh” was the dreaded number, even for my youngest visitors. From ages 29 to 39, each woman anticipated this milestone with fear, acting as if her life would end the moment she passed into her fifth decade. In fact, a good number of my clients had so much anxiety about this critical age that it was the sole reason they first decided to see me. I myself was in my late 30s, and found myself sharing their concerns in more than the usual “empathetic therapist” way. Often at night, I stayed awake riddled with worries about what lay ahead in my personal and professional life.

It got me wondering: why was it that so many women—including myself—had such a powerful aversion to reaching 40? I began examining the psychological research, as well as popular writing on the subject. Someone must have explored the anxiety that the fifth decade triggers for women and have offered guidance, I thought. But no one had. That is why, in my thirty-eighth year, I decided to write this book.

As we say goodbye to our youth, we lose our carefree sense of being immortal and having all the time in the world to figure out our lives. Many of us experience fear of the future. This book’s purpose is to help us remove our hands from our eyes and face our fears—and moreover, to transcend them. The truth is that our 40s can be a decade of loss, but those years also hold the potential to be a time of tremendous gain.

In the course of researching and writing this book, I facilitated discussion groups across America—from New York City to Seattle; Mississippi to Provo; San Francisco to Montana; Dallas to Chicago; Connecticut to Orange County; and Memphis to Washington, D.C. In addition, I conducted individual interviews with women from all different walks of life: from single mothers struggling to make ends meet to high-powered executives; from recovering crack addicts to Ivy Leaguers; from surfers to social workers to stay-at-home moms; from women in their late 30s longing to have children, to 50-plus-year-olds who already have cleared many of the hurdles we’ll discuss; from breast cancer survivors to victims of abuse, to women who have lost both their parents.

As part of this process, I asked the women to examine a long list of positive values that I had compiled. We then had a conversation about which of these values most served to sustain and enhance women’s lives as they entered their fifth decade. It soon became clear that the women—regardless of age, race, sexual orientation or socioeconomic status—all were powerfully drawn to five of what I call the Core Values.