(CNN) -- The biggest drugmaker in the world, Pfizer's brands include Advil, Robitussin, Viagra, Xanax and Lipitor.
Pfizer's most senior physician is Chief Medical Officer Dr Freda Lewis-Hall, a psychiatrist who describes her job as "a pinnacle role:" One that combines "the broadest potential impact" with "the deepest possible satisfaction."
Lewis-Hall grew up living with an uncle whose legs were ruined by polio. His carers, and his approach to life, inspired her to pursue a career as a physician.
A guidance counselor advised her to marry a naval officer instead, but Lewis-Hall says her family believed "that discouragement and dissuasion were just opportunities to sharpen your skills and deepen your commitment and prove that you could do anything."
Although the pharmaceutical industry is characterized by fierce competition, lengthy and expensive research and decreasing profits, Lewis-Hall says she finds her work exciting. "There's an unprecedented age wave worldwide. This puts us -- as humanity -- right in the way of many illnesses that are currently unaddressed."
"Over the next two decades, biomedical research will probably see advancement that tops what we saw in the last two millennia," she says, "and I hope I can be a part of that."