To think getting hit by a swing Is a life lesson? Everyone does it at some point at least once!
A friend and me took our dc's to the park yesterday and a lady was pushing her DS on the swing, friends little boy run out behind it and nearly got hit the lady then told my friend she needed to "take better care of her DS" as a "good mother wouldn't let their kid run around the park like that" 
I did have a word with her stating that she could of just said be careful and moved on but she was having none of it because we'd obviously left out super mum powers in the car
even if she ran she wouldn't of caught her DS in time
I mean everyone in their life gets hit by a swing at some point right? I mean that's how we learn to not run behind or in front of a swing when it's moving
yeah it hurts but that's life