My rst boss at Bell Labs had a habit of yelling. While he was an equal-opportunity yeller, when he shouted at me in my rst department meeting, I got up, told him when he wanted to talk, not yell, Id be in my of ce and walked out. I was 20 years old, just out of undergrad, and sitting among a group of aghast Ph.D.s. Perhaps this was not the best initial career move. But about 30 minutes later, he walked into my of ce and apologized. He never yelled at me again (though he did keep yelling at the rest of the team), and became one of three manager-mentors that shaped my career at Bell Labs and AT&T and taught me to manage others and myself. Ill share one story from each boss and the lesson I learned from each.