80% of your output will come from the top 20% of your inputs.

The 80/20 principle applies to many aspects of life too: 80% of value from socializing comes from 20% of activities/friends, so maximize those.

The Pareto Princple is a very useful Mental models for making decisions on where to put your efforts. It can help your personal Productivity as well.


  • Link to website, bibtex from Zotero or note with book/blog/etc summary