Mark Bertolini’s tenure as CEO at Aetna shows how inspired corporate leadership can invest in its employees, drive a higher level of customer service all while delivering a 629% total shareholder return over eight years.

Bertolini didn't get to the corner office through traditional means, however. Early in his career, he was known for the bare-knuckled leadership and hard driving competitiveness that led him to turn several companies around. But this ambition came at a cost, as he ran roughshod over his colleagues and employees and spent more and more time away from his family.

Two events served as wake-up calls for the hard-charging Bertolini. When his son Eric was...