As a friend was taking his son and his friends to a retro video game arcade today to celebrate his 13th birthday - I helpful related this story:
My brother took his son and friends to one of those big trampoline places. As lead dad for the day he'd envisioned every disaster (knee to the nose, elbow to the temple, getting trapped between trampolines, etc) so he was very nervous but it all went swimmingly, not even a bruise. So outside someone suggested a kick-about. The first kick of the ball hit one kid square in the face, he went down like a felled oak, bounced his head off the floor,.got knocked spark out and had to go straight to hospital to be checked over. He was fine but a bit sore.
Not sure what the moral of that story is: quite whilst you are ahead? You can plan for disasters but something can come at you from left field? You got away with it if no-one suffers a lasting brain injury? Duck?