You graduated at the top of your class, and then spent two years treating disease in third world nations. You learned a lot about humanity and how lucky you are to have grown up where you did. This motivates you to work as hard as you can to keep people healthy.
You open your own practice as an allergist. Your days are spent evaluating what makes people itch and sneeze. Then you get them the treatment they need. It's a great gig, especially because you set your own hours.
You are given the job of Health Commissioner for New York City. You start a crusade to get nutritional facts listed on fast food menus, tax cigarettes to make them unaffordable, and outlaw soft drinks that are over 30 ounces. These strides for healthy living catch the eye of the President.
You are selected to direct the CDC. You are instrumental in controlling flu outbreaks across the nation. You also become a major activist in healthcare reform by fighting to get all kids vaccinated, no matter the cost. This is a far cry from your days in the lab.
You were the director of the CDC, but have now accepted a job as President of Vacciplax, a $5 billion company that produces vaccines.