Opening a gym that is extremely cheap. Potentially free.

Hello everyone I am a veteran who was medically separated and I want to give back to my community. Mainly the veteran and active duty community. I would like for the 100% disabled vets to be free and I would like the active duty memberships to be very cheap. Ultimately I want this to be most affordable gym anyone can go to. I would like to know how to keep a business going while having a very cheap price for signups. I would like any advice on merchandising, ads, revenue streams etc. thank you all!