What Was the Biggest Mistake That Improved Your Poker Game?

Everyone makes mistakes while learning poker, but sometimes one mistake teaches the biggest lesson.
What was the biggest mistake you made that actually helped you become a better player?
For me, I used to focus too much on results instead of making good decisions. Over time I realized that reviewing my hands and learning from mistakes is much more important than whether I win or lose a single tournament.
I'd like to hear your experiences. What mistake helped you improve the most?

The biggest mistake that helped improve my poker game was playing too many weak hands. I used to call with hands that looked decent but weren't profitable. Once I became more patient and started folding more often, my results improved. I also began reviewing my hands after tournaments to learn from my mistakes instead of blaming bad luck.