I was a pretty active kid, not exactly sporty but I would always be off with my mate to the local BMX track or off over the fields at the back of our street with their dog.
I remember building a 'tree house' with a rope swing that we were really proud of at the time - in reality the 'house' was a big sheet of wooden fence panel wedged into the branches! My mate lost 3 teeth & broke his arm on the rope swing too...
When we got a bit older we used to go and hang round in a den that we had made on top of an old slag heap nearby that was covered in trees, daring each other to ride our bikes down the steepest bit we could find & generally messing about, experimenting with cigarettes for the first time & lighting campfires every now & then. A couple of years ago, the same slag heap had to be totally removed & re-lanscaped cos it turned out it was on fire underground the whole time!