I've long admired Clayton Christensen. My wife had the guts to ask his secretary to put me on his calendar. She did, and I got 15 minutes of his time. It was a surprise call, so when he was on the other end of the line, the best I could do was compliment him for the work he's done and his books (How will you measure your life, in particular).

He was so kind to take the time, and so genuine. That he would take the time to chat with a complete stranger for a few minutes has been one of the most important things I've learned from him, notwithstanding his books, talks, and theories.