When my sons were very young (before they were even teenagers), I used to take them to Laurelhurst Park and we'd feed the ducks, watch the swans, then retreat to the playground and I'd sit in a swing and watch them climb like monkeys on metal structures and run with glee saying, "Mommy, Mommy, watch me!!!!"
And, I did... My boys were a source of delight and joy as children and quite playful too.