Just last week I celebrated my 40th birthday. I suppose it’s a milestone of sorts, but it didn’t feel that different than other birthdays.

Now, a birthday—whether it be one of the “big ones” or not—is technically just another day. And yet certain days—like birthdays or New Years—command our attention more than others.

Regardless of whether they should or shouldn’t, the fact that they do can be of great benefit, since they can be valuable reminders to reflect on the trajectory of our life. They provide an opportunity to be thankful for what’s come before, and to consider what lies ahead.

Of course, we can reflect on our life any day of the year. But it’s all too easy to move through most days without paying much attention. We get busy. We get bored. We just want to get to the weekend, or the end of the semester, or till when the kids are out of diapers.

And then certain days on the calendar come along, and we tend to pay more attention. Once again we’re confronted with the reality that time keeps moving regardless of whether we like it or not. And although this realization is not always pleasant, it can provide motivation to make the most of the time we still have.

So, although 40 feels a lot like 39, I’m glad mile markers like birthdays exist. They provide reminders to celebrate the past and give thought to the journey we’re on—actions which can be all too easy to neglect during other times of the year.