Seriously, he’s done so much good. There’s a nonzero chance that the only thing keeping him alive is his desire to do more to help. For example, Carter has said that he wants to witness the eradication of the Guinea worm,a parasite that he’s been working on stopping for decades.

“I would like to see Guinea worm completely eradicated before I die,” Carter said at a press conference in 2015. “I’d like for the last Guinea worm to die before I do. I think right now we have 11 cases. We started out with 3.6 million cases.”