When I first started shooting offhand high power I could barely keep my shots on the target. I started running and doing exercises including pushups, curls, and situps. I also do wrist exercises where I have a weight tied to a string and I wind it up onto a dowel by twisting the dowel with my hands. After about three months of that, I started shooting mid-180s consistently, and have a few 190s to my credit. Used to, after about ten rounds my arms would start hurting from holding the rifle up but anymore I don't even notice it -- in fact, it seems like I get more stable after the first 5 or so shots, and then don't get tired for at least 40 more. I have found it makes a significant difference not to work out the day before I shoot. If I do, then the shaking comes on much sooner.