Physical Therapy with the Big Ball

I don't know much about the bill inflated balls that many rave about for exercise, but my Physical Therapist at the VA started me on one today and WOW! What a work out!
I was a bit timid doing them on a hard floor, but once he orders mine and I get it, I'll be doing these exercises at home on a carpeted floor.
Those various exercises not only work you out, you use more muscles and also your brain to help you balance.
My Therapist says he doesn't normally use these for most patience because most patience at the VA are much older and rickety and could hurt themselves. I am so excited I cannot wait until I get my ball!