How to master the 80/20 rule:
[1] List outcomes you want (revenue, grades, fitness, happiness).
[2] Trace inputs that cause those outcomes (clients, topics, exercises, habits).
[3] Measure: estimate which 20% of inputs create ~80% of results.
[4] Double-down on the vital few; schedule them first.
[5] Cut, automate, or delegate the trivial many.
[6] Review weekly; 80/20 your 80/20 (stack the effect).