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The more you play the more you learn to minimize un needed arm and wrist action.
One the the ways i learned to easily find the right string to pick and the notes to actually strum was by having my Pinky(when not using it) lightly anchor on the top of the guitar right below, or sometimes touching the treble E string. It helped me to only use the amount of arm and wrist motion needed at that moment of picking. I do practice a lot with my eyes closed and have kind of developed a “feeling” for picking he right string with having to look at it. All of it takes time.
i also try to warm up using the therapeutic squeeze ball and the Chinese metal balls a few times a week.