Arts & Crafts
Nothing beats some raw creative output. The problem is the fingers don't always do what the brain wants them to do.
Pick up a pencil, grab some paper, and start making waves! No seriously, start drawing waves, layer by layer. This will strengthen the muscles in the hand and improve dexterity.
Once your hand aches, put the pencil down and try again the next day.
More content will be released as time permits.