Now that your kid has started taking active participation in school activities other than studies, you will notice that he has become all the more attentive to what he is doing. Also, now he can identify his own mistakes, see where he is going wrong and can even correct himself if required.
What you need to know
If you think your kid is being overly harsh on himself then make him understand where he is actually wrong and where he is not. Also, be a guiding light for his improvement areas instead of criticizing him for the mistakes he's making.