Beginning in February 2007, Nielsen began playing a small role as a doctor in the humorous yet educational television show "Doctor*Ology". The show chronicles real-life medical techniques and technology, on the Discovery Channel. Nielsen said: "There are any number of things that you think about when you ponder if you hadn't been an actor, what would you be, and I've always said I'd like to be an astronaut or a doctor. I have such admiration for doctors. I just don't know how you go around to thank them enough for coming up with the world's most remarkable new discoveries."