I've been on paternity the past few weeks, and have spent some time reflecting. Below are some lessons - thoughts, really - that might have been useful had they occurred to me earlier. Note: The list below is decidedly incomplete; your mileage may, also, vary.

It's really hard to overcome a bad say/do ratio. Some people prefer to use ambitious time estimates as an incentive to work harder, but I've never seen that approach work. Do what you say you're going to do, when you say you're going to do it.
If you're not being listened to, stop talking. I learned this first while training my dog. Being ignored doesn't help anyone.
Strong argumentative skills beat weak argumentative skills, but it's only a debate if the other person cares.
"No" is a vastly underrated answer. One would expect it to be right about half of the time, yet most people (citation needed) are shocked when someone actually says it.
Long games are really hard to win if you don't pace yourself. Know what kind of game you're playing, and calibrate your patience level accordingly.
Jobs only add up to careers if you're capable of sacrifice. If not, you'll probably need a business of your own.
The satisfaction of watching Michael Clayton again never really translates into material effects on the rest of your life. Escapism has diminishing marginal returns.