(This post may contain affiliate links). The Stability Ball is a fun tool that also illustrates the healing effects of exercise. My son loves to use the Stability Ball to complete his required PE every day. In fact, it has made PE much less stressful for me and much more enjoyable for him.
The Stability Ball is not only delightful to use, but it is inexpensive, and fairly easy for beginners to learn. All you need is a little space, the ball, and some instructions, and off you go!
For example, we live in an apartment, and we have less than 3 feet by 10 feet at the foot of our bed to do exercise indoors. We do our PE in that area every morning for school. One of the things Nathan likes to do is just lay on his belly on the stability ball and rock back and forth. Not only does this provide him with sensory stimulation, but over time his core muscles (abdomen, back, etc.) will become stronger. And he doesn't even think this is exercise!