I'm in a similar situation to the OP despite being almost a quarter century younger!
I have MS and osteoarthritis, and have undergone bone removal surgery to both thumbs due to the horrendous pain I've endured.
I've bough pre-mashed potatoes from most of the supermarkets, which I've found to be perfectly suitable for my needs. I've also taken to keeping a bag of frozen mash, both Aunt Bessie's and the supermarkets' own brands are good, and I've also always got a couple of packets of the Idahoan powdered mash in the cupboard.
As far as I'm concerned, all of the above are suitable substitutes for me having to mess about with peeling and chopping potatoes.
I've even taken to buying other vegetables both ready prepared and frozen. You still get all the nutrients, worth none of the pain!