one thing I would like to add to Denise’s excellent advice: without money from an external source at all, you can start a walking program, and you can do it immediately. It often takes only for somebody to say where and when to meet, and people will go. The greatest obstacle I hear about walking is that people say that they do not like to walk by themselves.
This would be a good way to get started, and it does not preclude you from looking at other avenues that may be more professional and comprehensive.
I wish you good luck.