Regret Minimisation — To maximise your long-term happiness, prioritise the projects you’d most regret not having pursued by the time you’re old and looking back at your life.s1
This is my favorite mental model! Jeff Bezos applies this mental model in life.s2
Ask yourself: If I don't do this, will I regret this when I'm old? If yes, prioritise this project.
Then, apply the Pareto Principle to maximise output.