I had a regular exercise regimin that was cycling, pushups/situps, leg lifts - the usual stuff. When I picked up a Glock 34 I had a lot of trouble shooting it so, I now have a regular exercise regimin designed to strengthen my grip and be able to hold that Glock out there steady. I do running and cycling when I have time but my exercise regimin now is:
Reverse wrist curl:
And I also work out with these things called Meridian Balls or Bao Ding balls. I have some large carbon steel balls that are pretty heavy - somewhere around 1.25 lbs each. The idea is to rotate them clockwise and then counter clock wise in your hand without the balls touching.
The guy in this video makes it look easy, but it's not. And when I do this 200 times with 1¼ lb steel balls - all the tiny muscles in my hands are sore - which is a sign that they are getting worked out.
I notice all these things are increasing my forearm, wrist and finger strength and it is paying off with more accurate shooting. I noticed an improvement in my dry firing follow through in about 2 weeks.