I have wrist pain. After eight years as a cleaning lady (and a cleaning lady in a hurry) in my 30s and working on a keyboard in my 40s and 50s, I've wondered how long I am going to be able to make jewelry. Sometimes I have to wear a brace, and although it is ugly, it helps enormously.
I never thought there was anything I could do about my hand. When friends ask me to make them a hammered bracelet, I just laughed. It couldn't happen.
At Revere Academy, we made a bracelet from large jump rings. My bracelet was 40 rings - each one needing to be closed with muscle. I wondered about my wrists.
You know what? I had NO problems! Alan recommended a posture. He plants his feet firmly on the floor, each braced against the inner legs of his bench. He holds the ring in his left hand, braced tightly against the bench pin. The right hand does the bending, but the power comes from the legs and the back.
The same goes for filing. His "steel rod" method relieves the wrist of the work. The power comes from the back, the shoulder, the upper arm. No more wrist concerns. I can work forever!
An additional tip, as detailed by our bezel teacher, Vasken Tanielian: If your movements are consistent, like a machine, you know where your tool is all the time. Bring your metal to the file. Turn the metal instead of the saw. You'll get used to your saw being straight and you can count on it. You can train your file work to be at the angle you need.