I bought a balance ball!! This ball dosen't need any space. and I can do it when I like, watching TV,listening music or Radio and reading book :-) Just sit on the ball without using hands and foots is really difficult. I can't keep the pose for long time. There is more difficult pose."stand on the ball"I haven't tried it yet.Because If I lost the balance, then hit my head to floor and dead,my family will regret. And it's not good way to die, is it?