My kids are college-age, in the prime of their lives, and thriving in every way.Meanwhile, I'm struggling with the woes of midlife, and I feel envious of their youth.I am persistently trying to accept this and find the silver lining.I recently found a gray hair in my eyebrow, and my heart skipped a beat.I suppose it might be comical to those who have accepted aging and the speed at which life passes us by, but that's not me not yet, anyway. No one ever told me that eyebrows turn gray. I suppose no one really had to. I mean, I'm sure I've seen gray eyebrows before, but I never imagined I would fall victim to this atrocity especially not so soon.This unexpected gray hair just like every wrinkle, hot flash, and new joint pain was a reminder that there was still so much I wanted to do and even more that I wish I had done already.And just as I angrily plucked that sucker right out of its place, my daughter walked in. "Are you almost done? I need to curl my hair."My beautiful, young daughter, Nora, is about to decide where she will attend college next fall. She is excited about prom, graduation, and her upcoming senior night for hockey. Her hair is thick and gray-less. The world is her oyster and she doesn't even know it.Molly is my oldest daughter. She is about to study abroad in Spain. She is dedicated to fitness, has correctly identified her deepest passions, and is pursuing them with ambition and confidence. She is one of the bravest people I know. I look at her and see nothing but a vibrant, fulfilling future. The world is her oyster, too, and she just may know it.To be honest, I'm jealous of my daughters. They have everything ahead of them, and it feels like my life is behind me.I often find myself envious of my daughters' youthfulnessI am so incredibly proud of my girls. They have grown into such dynamic, wonderful young women, and the world is a better place because they are in it.If I am being honest, though, I can't help but feel a pang of envy when I observe them living their best lives. They have youth and time and their whole lives ahead of them. Sometimes, I want to warn them that before they know it, they will wake up with gray eyebrows and an ex-husband.Other times, I find myself selfishly living vicariously through them as if their experiences are indeed my do-over at life. I often yell at them, "Show me pictures from that party last night," "Let's find a fun place for you and your friends to go dancing this weekend," or "You should major in this and not that."I'm worried I wasted my youthI often say I have no regrets in life, but this gray hair reminded me that I do. At times, I am desperate for a rewind button.I wish I could go back to my teenage years and choose a different college, complete a different major, and take a new journey altogether. I dream of going back to the days when I consistently weighed 138 pounds so that I could appreciate that as skinny and fit rather than berating my young self for being "fat."I also want to redo my love life. I want to take the wisdom I have gathered from every failed relationship. I want to say "no" to those who caused me pain and "yes" to those who had the potential to love me the right way.I want to prioritize financial wealth because, as an 18-year-old, I naively thought my husband would take care of "all that stuff." As a result of that false belief, I now live paycheck to paycheck.I'm finding ways to accept and appreciate my agingDon't get me wrong, I am often happy. But at times, life is hard. What's even harder is looking into the mirror and realizing that I have lived more years than I have left.I often wonder: Are my best years behind me? Did I take them for granted? If a genie granted me a wish, would I truly go back in time, and if so, would I cherish the gift of time more?Of course, there is part of me (maybe a very big part) that would love to be 16 again but I want to be 16 with the wisdom of a 46-year-old. I suppose that proves aging isn't all bad, thanks to everything I have learned.I do know one thing, though: Today, I am the youngest I will ever be. I suppose there is a 75-year-old version of me in the future, with a full set of gray eyebrows, wishing she could be 46 again. Or perhaps my 75-year-old self will fondly remember 16 and 46 while feeling joyful to be 75, living in the present, and appreciative of all that is possible.I think my 46-year-old self would be wise to listen to her.