Have you read the picture book Love You Forever by Robert Munsch? I received it as a gift about 6 years ago before my first baby was born. I've read it silently to myself a few times and have always cried all the way through.
A couple of nights ago my 3 older kids asked me to read it aloud to them. I started it and, of course, started to cry. (This has happened several times, so I had never finished it for them.) Well, this time they insisted. I didn't just cry, but bawled, all the way through!
I don't know if it's just that it puts things in perspective about how these kids who can make life so difficult and crazy at times during the day are so precious when the evening is calm and they're asleep. Or maybe it's just the reminder once again that they grow so fast and too soon will be gone (from home), and then, too soon, I'll be gone (from earth).
If you haven't read it, go check it out of your library–but keep a box of tissues with you!