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Step out of your comfort zone, you need stress to grow and improve your chess.
Stop guessing, start thinking. Not only in your moves but also in the opponents responses
Stop solving exercises looking from your side of the board, you need to spot tactics regardless of the side of the board you're in.
Repeat the same problem set several times to help you spot patterns (just as in The Woodpecker Method)
Apart from programmed repetition. Repeat the problems you failed at will, whenever you want.