Here you are, celebrating a birthday. Here you are, marking another milestone. Here you are, making another notch in the doorframe.

As the ancients say (and as we say on our parenting medallion), tempus fugit. Time flies.

It sneaks up on you…and even when you catch yourself noticing it, the full weight of the conclusion can escape us. By the time they’re 6, as another famous expression goes, most of the truly important things they’re going to learn in life have already been learned (or not). At age 9, they’re approximately halfway done living with you! By the time your kid is 12, you’ve already spent the vast majority—around 75%—of time you’ll get to spend with them. At 15, they’ve got maybe 5% of their height left to grow, have developed the ability to think abstractly, and likely have just 3 years left of living with you.

And, if you had kids when you were 35 or older, by the time they’re 25, you’re well into the final third of your life.

It’s crazy. It’s painful to think how little we have left, how little is left of their childhood, how little time there is left, period.

You can let that thought depress you…or clarify. You can let it overwhelm you…or you can see and cherish every single moment.

Knowing these things—thinking about how quickly our time with them goes—can actually be a wonderful gift. It helps us realize how precious all of these years and weeks and minutes with them are, and helps us choose to make the most of them.