Clayton M. Christensen

I helped start a ceramics company called CPS Technologies. We took it public in 1987 at $12 a share. Three months later, there was this horrible cliff: Black Monday. Fidelity had bought 15 percent of our stock, and their algorithm caused them to dump it all onto the market that day. We dropped from $12 to $2.

The closer I get to retirement, the more I feel it will be a huge change, a shock, because athletics has been the core of my whole life. I know I'll miss the feeling of running fast, the adrenaline rush, and hearing the crowd cheering me on.