The wing of our school where I teach is two-story and rectangular, with staircases at every corner. I put together a playlist of energetic songs on my MP3 player that lasted 30 minutes. During the first two songs, I just walked briskly around the rectangle upstairs. During the third song, I went up and down the staircase at every other corner, for a total of two staircases during that song. Then for the fourth song, I went up and down the staircases at every corner, for a total of four staircases for that song. Then I reduced it to every other staircase again for the fifth song and just walking again for the sixth and seventh song.
I have been doing this since September. My first workouts included 8 total staircases. Now, in the same time period, with the same songs, I do 26. I still walk between them but I added more and more staircases. My next step will be to start doing double staircases; up and down twice before continuing around the rectangle. It's working. I've lost 46 pounds so far and I intend to keep it up until I'm down 64 more for a total of 110. It doesn't cost me anything but time and effort and it's totally worth it.
Find something you can do with the resources you have. It doesn't have to cost anything. The opportunities are out there. Find them and good luck!!