[H]is data suggest that a lack of opportunities for unstructured, imaginative play can keep children from growing into happy, well-adjusted adults. “Free play,” as scientists call it, is critical for becoming socially adept, coping with stress and building cognitive skills such as problem solving. Research into animal behavior confirms play’s benefits and establishes its evolutionary importance: ultimately, play may provide animals (including humans) with skills that will help them survive and reproduce.
Most of my childhood play was unstructured. Decent-sized back yard, and a dad who resisted the urge to yell at us when we trampled it. (There were several patches where grass did not grow for about 12 years, from all the foot and bike traffic.)
I also live by the adage It’s never too late to have a happy childhood
(though I would never describe my childhood as being unhappy)