Worry never once healed a wound, or cured an ill.

It always aggravates, irritates, and, furthermore, helps superinduce the evil the worrier is afraid of.

The fact that you worry about these things to which I have referred, that you yield your thoughts to them, and, in your worry, give undue contemplation to them, induces the conditions you wish to avoid or avert.

Hence, if you wish your child to be well and strong, brave and courageous, it is the height of cruelty for you to worry over his health, his play, or his exercise.
Better by far leave him alone than bring upon him the evils you dread.
Who has not observed, again and again, the evil that has come from worrying mothers who were constantly cautioning or forbidding their children to do that which every natural and normal child longs to do?
Quit your worrying.

Leave your child alone.