It’s a full time job for 18+ years, on top of the things already in your life. It isn’t easy, but god damn it’s fulfilling to see them grow. They do get very funny when they hit 3 or so and are grappling with language. They become proper little people.
Slightly related: One thing I’d suggest is opening an email account for them, and any time they say or do something funny or memorable, send an email about it. I love reading through the hilarious things they’ve said across the years that you forget about, and I’ll give them the account when they’re older.
Personal faves are my 3 year old calling a compass a clock of the world and my other one at 4 years old telling my retired boss, who had just told him he’s grown since she last saw him, that she’s also grown, into an old lady. Or saying, when he lost his favourite hat, ‘that hat was a piece of my heart.’