It was an “ah-hah” moment at a college graduation that set me on the path. The ironic thing is that it wasn’t even my graduation. It was a speech given at my brother’s commencement by D. A. Henderson. Dr. Henderson co-led the worldwide campaign to eradicate smallpox. I was simply awed by the audacity of the effort he described. He helped spearhead the effort that wiped smallpox—a disease estimated to have taken over 500 million lives since the time of the Pharaohs—from the face of the earth. I was in medical school at the time and had been toying with the notion of a career in public health. Then and there, I realized that I could use my career to effect social change—on a large scale.