For nearly 15 years, I sent @tim_cook a weekly report every Sunday night on the global App Store business. My team and I packed it with data, charts, and commentary on what was happening around the world. Most weeks: silence. Every so often, a probing question would come back about a specific metric or market. Or, better, a note congratulating us on a strong quarter. Those reports taught me a lot about discipline and accountability. No matter where I was in the world, I sent that report. Tim expected his leaders to know their businesses cold. Whenever I put anything in front of him, I needed to understand not just the numbers, but what was driving them and what we were doing about it. His expectations made me a much better leader. On my last day at Apple, Tim and I had a 10-minute 1:1 scheduled. We talked for 30. Reflecting on my 21 years at the company, he told me my greatest accomplishment wasn’t helping build a $1 trillion App Store ecosystem or helping scale the business to more than one billion customers. It was the team I had built and the leaders I had developed who were ready to step up after I left. That meant the world to me. We took this photo together right after that conversation. Today is Tim’s last day as CEO of Apple. Much has been written about what he and the company accomplished under his leadership. But perhaps his greatest legacy is the one he taught me to value: the people he developed, the culture he shaped, and the leaders ready to carry it forward. I’ll always be grateful I got to be a part of it.