Might I add fulfilling to the list? I find that successfully caring for my kids (and even my foster kids) brings a great sense of rightness that I can't ascribe to anything else. And there is something very calming, almost sleepy, about snuggling with a baby and rocking them. Even more so when it's your own child and you're probably also exhausted on top of everything...
My eldest is 9, and it still constantly amazes me at how fast he's grown. It seems like yesterday he was a wailing infant and I had NO clue what to do with him! I also have a 6yr old and a 3yr old; all three are beautiful, healthy, brilliant, sweet boys and I wouldn't trade the last ten years of child bearing and rearing for anything else on the planet.