Welcome back, Lynda!
The use of fitness centers on Disney Cruise Line's ships are included in the cost of your cruise, so by all means, go try them out! When you first arrive on the ship, stop by Senses Salon and Spa and the fitness area where you can pick up some fliers about the offerings in those areas for your cruise. You'll find that many of the classes are free of charge. A few seminars will be held as well. On my last sailing two of the seminars offered were "Detox for Health and Weight Loss" and "Secrets to a Flatter Stomach" among quite a few others. I'm sure you'll find similar offerings on your sailing.
There is a body sculpt boot camp available that does carry an extra cost, as well as the personal training that is available for guests at an additional cost. Check out some of the offerings you can expect on the
Disney Dream Fitness Center's page under "Fitness Activities". Once onboard, though you'll find a schedule of classes and their associated costs (or you'll see that many are free as well).
I hope you do participate in the Castaway Cay 5K fun run! I'll be running it myself for the first time this fall and can't wait! Just remember that is is much warmer in the Bahamas and humidity can be higher than you're used to at home, so make sure you're well hydrated and have a fun run!
Do check out the running/walking track on the ship too. It's a nice way to get in some training runs while you're onboard, and honestly, I can't think of a more beautiful place to run than around the Disney Dream while looking out at the ocean!
Stop back with more questions, Lynda! I'm happy to help!