When Reckitt Benckiser CEO Rakesh Kapoor was young, he was given a bitter-tasting medical treatment that he endured without complaint. A similar level of stoicism is a prerequisite for successful leadership, Kapoor says. "You have to swallow many bitter pills in your life," he explains. "You just can't keep complaining about how life should be. You've got to accept the way you have to run your life and then do the very best you can."