I turned forty years old yesterday. It is my personal record for longevity. As I reflect on this milestone, this unavoidable step into a new decade, I find that I feel surprisingly peaceful about it.

The day before, the last of my thirties, was something of a big day. My company had an open house (a coming of age for the firm) and a birthday party for me in our new offices in downtown Washington, DC. Many friends stopped by and ended up hanging around well past nine. It was a good excuse to share food and celebrate.

When we cut the cake and everyone sang the birthday song, I had the opportunity to make a speech, which I regret to say I did not take. I only whispered a quick thank you and remained otherwise quiet, giving in to my shyness and tiredness from hours of caring for my under-the-weather, three-year-old daughter. I wish I had the presence of mind to tell a quick tale about how the company came to grow from a one-man firm in an attic to what it is today. And to note how much everyone in that room played some part in helping me to grow along with it. In any event, I was happy to be among friends.

This birthday reminds me of the day I turned twenty-five, now an astonishing fifteen years ago. For some reason, that milestone felt like a bigger deal. I remember thinking about how I had completed my first quarter-century, and how I wanted to do better with the next twenty-five. I took a hike with some friends into the Rocky Mountains above Boulder, Colorado. Seems like yesterday.

If I were able to go back in time and advise that twenty-five-year-old former self, I would tell him to move quicker past some stages of life where he got stuck and to focus more on being true to himself. I would tell him to marry and have kids sooner, to waste less time, and to play more. But if I were twenty-five again and could pick the path that would lead back to where I am now, I might just take the same one again—there is much I am thankful for.

Our lives now are busy, complicated, and stressful—but also rewarding. Nothing is close to perfect, nothing feels secure, nothing is constant. I hardly ever sleep through the night, catch up on all my responsibilities, or maintain control over many aspects of my life. But I also find much more in each new day to experience, to learn from, to navigate, to contend with, and to be grateful for.

When I was twenty-five I told myself, a bit aimlessly and without real commitment, that I should seek a second quarter century of excellence. I started slow on that decade and a half, but gathered some steam of late. Today I hope that I am fortunate enough to make it to eighty and to make it to that age in such a fashion that I can look back on a second forty years positive about another big milestone.