There have been times where I've said, "they grow up too fast". If you have kids, you've said that, right? I no longer believe it.
It's only "to fast" if you're not paying attention. As a parent, I am in a perpetual battle to stay present and embrace every stage.
Nostalgia is good in small doses...but in large gulps it's intoxicating. To much yearning for the past keeps us in the past.
So I suppose it's not, "they grow up too fast" but "they grow up fast enough." Fast enough gives me just enough time to enjoy every stage.