Hi Georgina!
Thanks for your question. I do understand keeping the exercise going while being on vacation, and certainly
Disney considers providing as many amenities that accommodates fun, entertainment, and certainly health and wellness for all its wonderful guests.
Disney's Port Orleans Resort - Riverside is a beautiful resort, that includes a
jogging trail and even bike rentals, but unfortunately, no fitness facility at this time.
I spoke with
Disney Guest Services, and they mentioned that you would have to be a guest at a Disney Deluxe Resort, which would entitle you to use of the fitness center at the Deluxe resort you're staying, as well as other Deluxe resorts on premises. They do not offer day passes at this time.
Hope this helps. Have a Mickey Magical Day!
Terry