The following is an excerpt from the new book "Magical Journey: An Apprenticeship in Contentment" by Katrina Kenison.

I tried to sneak past my fiftieth birthday without a celebration, stunned to realize I now had fewer days left on earth than I’d lived already. And, having crested the arc of life and begun to make my way down to the other side, I’m a little weak-kneed, unsure of my footing on this scrabbly descent. How am I supposed to feel about aging in a world where beauty is younger than 40 years old, where wrinkles mean it’s time to consider “getting some work done” and where I often feel invisible when I enter a crowded room? Going down turns out to be harder than climbing up; it seems there’s more to this second part of life’s journey than meets the eye -- and without the familiar landmarks of day-in, day-out family duty to keep me on track, I’m not at all certain of the path.

The ache I feel deep in my breast this winter is not assuaged by any of the tasks that used to add up to a life. I manage to stay busy all day, then lie awake at night, worrying about things beyond my control. I remind myself to live in the moment, yet carry a deep sadness for moments already gone. I reach out to my teenage son and feel not the old, easy intimacy I long for, but an assertion of his new independence instead; our relationship, healing slowly, is still raw and tender to the touch, like second-degree burns on my heart. Henry, busy and thriving at college in Minnesota, takes pride in his self-sufficiency. He calls to say hello, to tell me his news, but rarely to seek my counsel. Perhaps that means I’ve done my job well -– he knows who he is, how to take care of himself, how to create a life -- but it also means that after all these years of dedicated service, I’m essentially unemployed. I answer e-mails, pay the bills, read and write, take care of the house, spend time with my husband, bring lunch to a friend. The days are full enough. And yet, the question nibbles at my edges: What now?

At times, my nostalgia for our family life as it used to be -- for our own imperfect, cherished, irretrievable past -- is nearly overwhelming. The life my husband and sons and I had together, cast now in the golden light of memory, seems unbearably precious; what lies ahead, darker and lonelier and less enticing. As Franciscan priest Richard Rohr has observed, our egos “prefer just about anything to falling or changing or dying.” The second half of life seems to demand that we grow familiar with all three.

So many of the things that have shaped my sense of self and filled my life over the last two decades have slipped away –- my career as an editor and the steady income that went with it; the day-in-day-out responsibilities of parenthood; youthful dreams and ambitions; my bright eyes and smooth, taut skin; even the simple expectation that I would put two meals a day on the table and the family would show up to eat them.

It seems that, just as our children are coming of age as young adults, we women confront some coming-of-age rites and passages of our own. Whether we are eager and ready for change or have it thrust upon us, we find ourselves in new territory, a little lost and fumbling for direction as the years suddenly seem to pick up speed. Thirty, 40, 50 -- how could three-quarters of my life be over? Where did it go? A few months ago, I sat at the bedside of one of my dearest friends, holding her hand as she drew her last breath. Not a day goes by without the pang of grief and an awareness of all she’s missing. Losing her, I feel even less certain of my own footing, as if ground that only recently felt firm and solid has turned into shifting sand.

Meanwhile, in my own close circle of women friends in their forties and fifties, I see a breathtaking span of challenges and possibilities -- from divorce, illness and financial crises to new careers, revived passions and all sorts of creative endeavors; from unexpected romantic relationships to adult children struggling and in need of support; from a new ability to say no to unwanted demands to renewed commitments to community service, friendship and extended family. My friends are climbing mountains, passing the bar exam, learning to live with chronic Lyme disease, recovering from a husband’s early death, taking up cello, selling the family home, volunteering at a community garden, taking painting lessons, caring for elderly parents. What amazes me most is not the range of these experiences, but the fact that none of our lives today resemble the lives we took for granted just a few short years ago. What we all have in common is a sense of having reached a turning point. And, as we come face-to-face with the realities of our changing bodies, our changing roles, our changing lives, we are aware as never before that our time here is finite. Picking up the pieces of lives that have been transformed by change, rearranging them into new patterns, we wonder how to make good use of these remaining years, how to live now in order to avoid regret later. And we are compelled to meet our true selves at last.

Copyright © 2013 by Katrina Kenison. Reprinted by permission of Grand Central Publishing. All rights reserved.

Earlier on Huff/Post50:

Loading Slideshow...
  • Middle Age Myth #1: Midlife Crisis

    Research shows the midlife crisis is largely fiction. People in their 20s and 30s are more likely to experience the kind of "crisis" associated with middle age. Only an estimated 10% of middle-aged people have the classic midlife crisis.

  • Myth #2: The Empty Nest Syndrome

    Researchers have found no evidence of the so-called empty nest syndrome. Many parents relish and enjoy the transition, taking pride in the fact that all their child-rearing efforts have paid off, and their offspring are on the road to accomplishing their goals.

  • Myth #3: The Trophy Wife

    Men don't abandon their middle-aged partners for younger trophy wives as the stereotype suggests. Most marriages break up in the first eight years. The recent rise in divorce among the middle-aged is because second unions are breaking up (usually within the first eight years of marriage).

  • Myth #4: Menopause Stinks

    Hot flashes aside, nearly 62% of women in one survey said they felt "only relief" when their periods stopped, while fewer than 2% said they felt "only regret."

  • Myth #5: The Death Of Libido

    Despite the latest hype about testosterone supplements, low sex drive, depression and sagging energy levels were more likely to be caused by stress, poor eating habits and laziness in midlife than lower hormone levels. Meanwhile, many researchers think that warnings about female sexual dysfunction in middle age are highly exaggerated. What may account for women's flagging sexual life is that they are less likely to have a regular partner than men.

  • Myth #6: Health Inevitably Declines

    It turns out age really is about attitude: Research has found that believing that you can improve your health in middle age actually improves it. A sense of control in midlife can dramatically reduce disability and preserve one's health and independence later in life.

  • Myth #7: Happiness Plummets

    The truth is just the opposite: Many people view midlife as their happiest period. Several surveys have found that while happiness dips in the 40s, people start to feel more content with life after the age of 50.