If you had the time and opportunity to sit in on any college classes just for the purpose of learning about the subject, which classes would you choose? Why?

If I could choose to sit in any college classes I would choose health, and sports classes because I want to do something in that department. I would like to sit through health classes that have to do with how the human body works, I am interested in learning new things about our bodies and how they work. Health is the only thing I really find interesting.