Here are a few options for you:
I would visit as many Senior centers, retirement communities, physical therapists, and community centers. Also contacting doctors who specialize in older populations should also be part of your strategy. As for younger ages I would concentrate mostly on the local park districts, youth leagues and join moms networking groups.
It takes time to build the right network around you in order to get your business going, but at the end it will pay off. Facebook is a good option as well and a newsletter to your current clients/members will bring you the exposure you will need to build the necessary relationships.