It's kind of fun at my age to go back and talk to business-school people. I tell them, "I can summarize everything you need to know to lead a major corporation. Are you prepared to write this down?" And then they get all ready. I tell them I can summarize how I succeed as a leader: Listen to your employees, listen to your customers, shut the f - - up, and do what they tell you.

Strangely, from a life-change standpoint, I sold the company I was running and got divorced in the same month. And so there I was, at home, and I'm not the CEO. I took a few months thinking about what I wanted to do. When the first call came in about running a company owned by Deutsche Telekom, I thought it was laughable and really not something I'd do. I took the meeting mainly because the headhunter I knew. At first I thought I was just helping her fill out the roster, but then I dug into it.

When I used to live in Asia, they used to say, "If you're going to sing karaoke, you want to go after the worst singer." And I'd be coming in Deutsche Telekom after the worst singer.

On my very first day at T-Mobile, I demanded that every time I spoke publicly to the company, all employees across the country would be invited to watch. I faced legal and all that crap, but ultimately we were able to figure it out. We record it, too, so if somebody can't leave the sales floor, they can watch it later. Another thing I did very early on is give every employee stock, which we continue to do. So every time I speak to them I speak way over some of their heads.

I went, and my first interview was with René Obermann, who was the CEO of Deutsche Telekom at the time - wonderful guy. And right after hello, I told him that it was my opinion that he could only fail one way in the US. I said, "Do exactly what you're doing - nothing."

It's kind of fun at my age to go back and talk to business-school people. I tell them, "I can summarize everything you need to know to lead a major corporation. Are you prepared to write this down?" And then they get all ready. I tell them I can summarize how I succeed as a leader: Listen to your employees, listen to your customers, shut the f - - up, and do what they tell you.

My interaction with my followers on social media has become a phenomenon, and that's hardcore work every day! I have carpal tunnel from typing on my device.