Not shiny new equipment, but, a wee book called "Play Golf Forever: a Physiotherapist’s Guide to Golf Fitness and Health for the Over 50s"
Yes, it's hard to tell if I'm over 50, I know, but, this wee book is a straightforward guide to simple exercises that do , (and are) make a difference. Easy to follow and easy to carry out the instructions. Excercises can be done in the house, no need for a gym visit
Add to that a Foam Roller for helping to loosen the muscles in the hard to get to parts of the back. bananaman mentioned this to me a couple of years back, only just got one. Wish I'd done it earlier.
Here's hoping I can make some improvements to my "old man" swing for the coming season.