You need focus to become exceptional at anything. You have to be great at saying no. Massive amounts of time and energy are wasted optimizing things that should be left undone. What problems are worth working on? What skills are worth developing? What actually matters?

Experts can exist in narrow areas, but not broad ones. Experts exist for: -how to run a political campaign -how to set up a 401k -how to set a broken arm No experts exist for: -politics -the stock market -the human body The systems are too complex. Mastery needs a boundary.

To become successful, default to saying yes to opportunities. To remain successful, default to saying no to opportunities.

You can say yes to everything that really matters if you are strict about saying no to everything that really doesn’t.