There's a great variety of...

...sitting. 

It may be wiser to keep in mind that sitting is a form of ultra-slow movement, not dictated by the movement of legs. The effort to adjust into a new (or next) sitting posture might just be great exercise. The kind of effort (or greater) put into unconsciously changing sleeping postures to have a great sleep through the night.

What kinds of sitting does your current interior design offer? That chair, that sofa, that bed...

Those are Peter Opsvik's chair-designs.

I realize that the chair at my office is making me (my body) dull and weak. Offers no variety in this movement called sitting.