I was thinking that someone could create fun "action" cardio-workout courses. Instead of the Theme Park "action" rides where you let a cart do the walking. Think about any clich&egrav;d foot chase you've seen in an action movie, and it could be a simple story. "Dr. Yes set up a bomb on the top of this building... you have 10 minutes to reach it and 'disarm' it." "Watch these people on this crowded street for a jewel thief and give chase to that person."
A person might not have the stamina to "beat" a course on the first time, but you could still make even "losing" fun. You could even segment courses into "difficulty" levels.
The impetus for the idea came from the idea for an "advanced" course involving the standard movie sequence of chasing someone across several rail cars of a moving train. Obviously this one would take a person being in reasonably good shape and would require quite a bit of good supervision, but it would probably be "fun".
Add a musical score and "DVDs of your action adventure on sale in the Lobby!" and you have a commercial venture.