In the months leading up to my birthday this year, the big questions have often and repeatedly pushed into my thoughts: am I living the life I want to live? The life I was meant to live? Have I accomplished all that I should have by this age? (What is it, by the way, that I should have accomplished?) This was, you see, the year I turned 40.

Even just typing those two digits is surreal. Forty-year-olds can’t claim the hint of youth that thirty-somethings can claim (and that twenty-somethings possess outright). And the evidence is there. My body doesn’t recover as easily as it used to from exertion and injury. Also, forty is the age that women are supposed to begin getting yearly mammograms–how’s that for a sign of aging?

On the flip-side, I have less fear of people’s judgement of me, but more fear for the fragility of life. Fewer things make me panic, but when I do worry, it’s a can’t-sleep-at night kind of worry. The way I respond to life’s surprises has changed, and I hope it’s for the better.

I realize I’ve traveled many miles when I look back at the last decade: my belly has swelled and deflated three times with the growing of three new lives–well, not fully deflated, but that is a topic for another day. I have nursed those three infants for a total of almost three years. My family has suffered, and survived, the sudden loss of my father. I have completed a professional degree, accomplished some work missions that I am proud of, and written my first book. I have learned immeasurable lessons about forgiveness, bravery, kindness, love, and a number of other things that make us human.

The time for textbooks and swaddling blankets is behind me. Turning forward, I know that many personal and professional opportunities for growth and failure await me, as do more lessons in humanity. Looking forward, I also know that my mission, along with my husband, is to lead those three lives in our charge through childhood and adolescence and nurture them towards the best of themselves.

Forty is in part a look back at one’s life to see if any of those 14,610 days have been wasted, but it is also a reckoning that my life, assuming God grants me a long one, is half over, more or less. And do-overs are not guaranteed. Time is fleeting; you can neither pause nor repeat it.

If I miss enjoying my kids at a certain age, that chapter is gone. They keep growing and cannot revert. If I miss the opportunity to do something new, that opportunity may never come again. If I decide to give the markers of our lives (birthdays and holidays, for example) a pass one year because I just don’t feel like it, that occasion is gone. If I have the opportunity to lift a stranger or friend up in their time of struggle, and I do not, for whatever reason, I forgo that gift. The place for those memories is empty, and I think one of the things I fear most is to look at my life, both at its end and in the after-life, and find that where those riches should be, there is only emptiness.

So the question I have to ask myself is this: what do I consider riches? When I am old or gone, what will give me pleasure and pride to remember? What kinds of memories will allow me to say that I have lived a good, rich life? What memories are worth storing up? Whatever those are, that is what I have to pursue, earnestly, in the present.

Forty-year-olds are supposed to have it together and be settled in life. They are supposed to know themselves and have answers to all the big questions. I for one don’t have it together and the answers to the big questions evade me as much as they ever did. OK, maybe not as much, but neither do I have it all figured out. And in a way, I hope never to, because when you think you have all the answers, you stop asking questions. When you stop asking questions, you close yourself off to all the mysteries that remain unanswered in this wild ride called life. And this ride is one I very much am still on.