If you have the urge to get a piece of fitness equipment, I would get a step like the ones used for step aerobics.
You can step, lunge, squat, there are 100's of variations on the basic up down step, and it doubles as a weight bench... lots of possibilites. Most have removable legs so they are easy to store in a closet or under the bed.
They're cheap or you can even make one out of wood and nails if you are handy... or can convience someone who is to make it for you!
