What's the most difficult feedback you ever got and how did it change your life?

I asked my mentor at Harvard to watch me teach one day. He said okay. That night I prepared late into the night. The next day he sat in the back and watched. After class, like Odie the Dog, I ran to his office panting for positive feedback. He said, “Jim, you’re boring!”

THUNK! An arrow to the heart!  OUCH!

Then he went on. “I notice you play basketball with the doctoral students at noon.”

"Yes," I said. "I love basketball."

"Well, it’s apparent. You come back floating two inches above the floor, glowing, and exuding energy. You’ve got to figure out how to play basketball in the classroom."

I went away sad and confused. Basketball was playing, teaching was work. Never the twain should meet. Then it occurred to me: You have to start some way—there’s a tipoff. Then you pass the ball to others who dribble and do their thing. Then the ball is passed to another. Someone dunks it, we all go wow and then race down the court to the other end. 

The “ball” is who’s talking in class! You COULD play basketball in the classroom! And that insight changed my whole philosophy of teaching and how I approached it. And I was later rated the 2nd best teacher at HBS (after Michael Porter that year). That change was the foundation for 35 years of extra-ordinary experiences in classrooms all over the world.

BEST PIECE OF ADVICE I EVER RECEIVED. Thanks Tony. Rest in peace!