I do it too.
I have a whole list of things that I do to stim, and it seems to be growing.
I cannot stand to sit still, to me it is an "non-productive" thing, and I feel like I need to be productive. For this reason, I cannot sit and watch TV without ding something else at the same time. The only time I am "allowed", or "not required" to do something else while watching TV, is if I am watching something educational. Apparently, my brain sees learning as something productive. I smoke outside my home, and when I do, I have to pace. I cannot just sit there and smoke, or stand there, I must keep moving, even if its only a circular path, I must move.