My old foreman taught me to change my sanding direction every 15 minutes. Going from circles to straight up and down, then side to side, uses different muscles so no single tendon gets fried. It totally lines up with what @butler.kevin said about a lighter grip, because you're not locked into one motion. I also set a timer on my phone to force short breaks to shake out my hands. That combo saved me from the worst of the pain.

See, I'm the opposite of @thomaspatel on this. I always go for the big fix, even if it means a reset. My roses came back twice as strong after a brutal prune.

Remember how @sanchez.pat mentioned weak springs? That's what makes a silent shift so hard to get right.