Mental Models
Pareto Principle — 80% of your output will come from the top 20% of your inputs. To maximize ROI, preferentially invest in the 20%.
Every Action you take is a vote for the type of person you wish to become. No single instance will transform your beliefs, but as the votes build up, so does the evidence of your identity. This is why habits are crucial. They cast repeated votes for being a type of person.