Go to work the next day and try to do your best work.
Do this two months before the baby comes and you'll already be adjusted to your new mental norm.
I'm only half-kidding. The eradic sleep is tough - babies through toddlers wake up for all sorts of reasons. Depending on the child, it could be years before you sleep consistently through an entire night.
That being said, the first time your baby smiles at you, or when they offer a drink of their juice because they are being thoughtful, when they say "love you" the first time, when they are genuinely excited to see you after a long day.. No other feeling like it.