You can see problems that aren't appear in a double-spaced Courier typescript. ( Yes, you could do this in the old days on galley proofs, but that was an expensive luxury for most writers).
So Naval writes that when I talk about specific knowledge, I mean, figure out what you were doing as a kid or teenager, almost effortlessly, something you didn't even consider a skill.
I think also being a police officer requires you to get your hands a bit more dirty; maybe use physical force to restrain criminals, maybe be faced with very difficult situations as well.
If it's an old friend who knows where you live, it might be an old friend that you're going to want to look kind of stunning for but not too effortful.
The more of the details of our daily life we can hand over to the effortless custody of automatism, the more our higher powers of mind will be set free for their own proper work.