The Nutty Professor Fitness Instructor was played by Eddie Murphy.
Although the Fitness Instructor looks like Richard Simmons the actor who plays the Richard Simmons Look Alike is actually Eddie Murphy who is a really great actor.
I also thought it was indeed Richard Simmons playing the Fitness Instructor but it was Eddie Murphy instead.
Eddie Murphy plays a lot of the parts in the Nutty Professor movie.
Eddie Murphy plays a total of seven characters in the Nutty Professor film.
In fact Eddie Murphy plays every member of the Klump family except for Ernie Klump Jr., the nephew who is played by actor Jamal Mixon, as well as the Richard Simmons Look Alike.