I have this chair at work that is an exercise ball balance chair. It’s one of those Pilates balls that sits in a base with wheels, and it’s supposed to be more ergonomically friendly than your standard Mad Men-era office chairs. (Between you and me, until this thing starts making my coffee as soon as I get to work in the morning, the jury’s still out on how much friendlier it is.) I inherited the chair from my predecessor in the office, a yoga instructor who swore by the healing properties of the exercise balance ball. Seeing that my existing …