This is true and important aspect too, we have to concentrate on only those aspects on which we can take action because aspect on which we will not take any action is just waste of time because we will going to give stress in unnecessary things.
I really liked the example which you gave means, take that much which you can eat and that holds the great message because if we put all efforts in unnecessary stuff then we are just increasing our headache for sure and it is nothing good for sure.
Both positives and negatives happen on this Platform and it's just not about the platform because these are life aspects means we see both positive and negative aspects but we have to remember that, if we can improve it then we can take initiative otherwise you are just hurting yourself.
Wishing you an great day and stay blessed. 🙂