SO IN MY EARLIER POST ON THE BALANCE-BALL CHAIR, I WAS SKEPTICAL: But one of my longtime readers emails: “I started using a balance ball as an office chair two years ago, and it literally changed by life. I no longer stoop like an old man when I leave my desk, but stand tall and strong. I have more energy in the evening, and my lower back ‘lock-ups’ are a thing of the past.”

UPDATE: Another reader emails: “I’ve sat on an exercise ball for five years now – at work and home. Used to have back problems – enough to lay me up in bed a couple of times a year, several days at a time. It hasn’t happened a single time since I started sitting on the ball.”

Okay, so I cracked and ordered one.