In 2011. I noticed I was getting fatigued at the range doing offhand shooting. After 20 minutes or so of shooting I couldn't hold a steady sight picture, my arms were trembling.
I was a little amazed at this because I hadn't had the problem before, and every morning I do pushups, situps, leg lifts and I curl 30lb dumbbells. I also ran and did cycling.
At that time I also purchased a Glock 17L, and I was not able to dry fire it and maintain good follow through - the sight always twitched to the right. I had people tell me I had to pull the trigger more slowly - more slowly still. I had people tell me I needed stronger fingers so I could do a smooth pull...
I started doing research and I added different exercises to my workout. Basically I focused on adding muscle mass to my forearms and increasing the strength of my fingers / hands.
I have a routine now that I do to keep muscle mass in my shoulders and forearms, as well as keep my grip strong, and it has made a huge difference in keeping a steady sight picture, and being able to shoot better for extended range sessions: