It's been said that "love is a better master than duty," and requiring college students to take a physical education course sounds like a duty.
If you want people to exercise without coercion for the rest of their lives, I think you have to tap into intrinsic motivation, i.e., the unique things that get you excited. Depending on your personality and life experience, that might be novelty, socializing, recognition, or competition.
Forcing college students to exercise will backfire, leading many of them to stop as soon as the course is over.