This means, if you’re a 100, they will be an 80. And this is not necessarily a bad thing: 80% is good enough for most tasks. Your apprentices and employees are doing the tasks that are not essential to you, anyway.
This also means that if your performance dips to an 80, they drop to a 64 (I hope my math is correct there).
No one is going to work harder than the person on top. They do what they see you doing. And since they’re not as good as you anyway, when you slip up, imagine what their slipping will look like.
You must lead yourself before you lead anyone else. Your actions will lead your followers.