Two weeks into his freshman year at Harvard, David G. Ewing tore his Achilles tendon clean in half. The football career he had been recruited for ended before it started, and he spent the next year learning to run without a limp. That early gut check became the pattern for everything that followed. A cancelled future in his family's Detroit manufacturing plant. A tech startup that imploded in the dot-com winter. A first employee hired on September 10, 2001. Every time a door closed, David figured out what he still had and kept moving.