I do not remember seeing this commercial back in the 1980s. As a big fan of the Peanuts, I think I would have remembered it if it ran in my area, especially because it teams up two characters who I really enjoy and don’t get enough teamed up enough, Pig-Pen and Lucy.
In the commercial, Lucy is the aerobics instructor and her pupil Pig-Pen just doesn’t have the energy to get through her workout. Lucy know this answer to his problems. Cheerios!