I also work at a desk all day, but I try to get some exercise through the day. I have a couple sets of dumbbells that I can do some quick arms and shoulder sets, and I try to hit the deck at least once a day for a quick set of push-ups.
My coworkers take smoke breaks, so I'm not cutting into job time while still getting at least some resistance training.
Would not only help your shooting, this might also help your other issues I'd think...just be smart about it...maybe use bands versus dumbbells...
Take Care,
Buzz

