What are some interesting ways for me to stay healthy, even away from home?

I’ve been using Wii Fit for at least half an hour every day for about two weeks and eating healthier. But now I’m at my mom’s house and we don’t have a Wii here, or very healthy food. I don’t have a bike here and I can’t go for walks because it’s not the safest neighborhood. I want to keep up with being healthier but still have fun with it, and the only things I can use to get any kind of exercise are the stairs and the empty backyard that we share with our tenants. This is important to me and any ideas will be helpful.