@Mr. Willy
Just remembered an exercise I'd do a lot when I was young and really putting serious time into guitar.
My mom was a nurse and I'd have her splint up one of my left hand fingers so it couldn't bend and then
practice that way for a couple hours. The only finger exempt was the pinky.
Ha, after playing, the 3 working fingers would feel like they just did a few reps with major weights.