I do the same thing, except that I have a much easier workout than you as I only live on the 5th floor.
Aside from all the strenuous activities that were mentioned, you can also buy this cheap exercise gadget called "Figure Twister", it will definitely make you sweaty in a few minutes. It targets your tummy and arms. here's how it looks:Log In
Walking is definitely my go to for something you can pretty much always do no matter where you are (even if only up and down stairs) and without any cost. There are many other exercises that would not cost much at all....running and many other cardio workouts, would also be a good place to start.
You can exercise for free if you use your initiative. You can do pull ups from a tree, squats, sprints, push ups, lunges etc. There are loads of exercises you can do which don't cost you a penny. You can also buy makeshift exercise equipment for very little money - water jugs, for example.
I think the list would be many and some cheap and healthy ways to stay fit would be to just dance around to some music and make it a workout,also hand weights are a fun thing to add to the dance routine. I think you could just go out and run-and another would be to hike to the park and workout,or just go for a walk with your dog which would be fun as well. I think youtube workouts and hiking on nature trails are both great ways to enjoy yourself. If you live in the city you could take a pack and do some urban hiking as well(walk around downtown all day).
For a housewife the work that gets done every day provides enough exercise and this with a daily walk, climbing steps and not taking lifts as far as possible are some ways to exercise without having to spend any money.