Yeah, Grandpa's back aches, and he recognizes the why. It has to do with uneven movement in the context of extended periods of sitting at a desk. There are several ways to handle this, and one is an inflatable ball that costs about a quarter the price of going to the chiropractor.
However, there was a reason for the low price, that being the supposed pump to inflate the ball. I'm not sure the pump is sufficiently substantial to respond to gravity, much less inflate the ball. This left me huffing and puffing, and that worked for a while, but human lungs can only go so far.
Enter the woman at work who sits on a Pilates ball all day instead of a regular chair. She says sitting like that builds her core. No, I have no idea. Nonetheless, she had a good pump, and she let me borrow it. She even demonstrated its use after I thought it was battery operated. That demonstration led to additional discussion and a bit of blushing. Okay, a lot of blushing.