The Imperfectionist: It’s worse than you think:

In a piercing recent essay that's well worth your time, Simon Evans writes about watching his daughter become an adult, and also about the death of a close friend, and how painful it is to experience the speed at which something as seemingly substantial as a childhood or a friendship is over and gone for good. Toward the end, he offers a few thoughts on how to make sure you're truly present for life – ways to "drive a stake into the shining moment." But I love what Evans doesn't do in the piece, too. He doesn't turn it into a lecture about seizing the day. Nor does he dwell on what he wished he'd done differently, thereby implying that there might be some cunning way to avoid the experience of loss. No, his essay suggests, it's worse than that: a life fully lived just is painfully bittersweet, the joy inextricably intertwined with loss. The major chapters of life, such as your children's childhoods, just will feel like they're over too fast, pretty much whatever you do.

You should definitely click through and read the Simon Evans essay as well.