Wow, where to start. Background, I'm an overweight desk jockey, with a serious case of arthritis, in my back, hips, knees, and ankles.
1) If you're still shooting Weaver, or Modified Weaver, the '80's called and it wants it's gun/holster/shooting style back. Using a modern shooting style, "push/pull" is not possible because your hands are on opposite sides of the gun, where they belong, according to the laws of physics.
2) Look up the Todd Jarrett YouTube video on how to hold a handgun, or look for Phaseline Green's videos on pistol shooting - I'm pretty sure Earl has a how to hold/aim video. Travis Haley explains it well in the Magpul Video
3) I can't say this enough....stop using the Weaver, it just causes issues - wait until you try shooting on the move, (virtually impossible) in Weaver.
4) Dry Fire - go to pistol-training dot com and look up the "wall drill" in the drills section, practice it until you get it right.
5) I'm living proof that physical condition is no block to accuracy, I'm lucky to still be walking, and I can shoot with reasonable accuracy.