This book explained everything to me.
https://www.amazon.com/Balanced-Barefoot-Unrestricted-Confident-Children/dp/1626253730#productDescriptionsecondaryyviewdivv1511461929027
Have cut and pasted this from the link:
'Today’s kids have adopted sedentary lifestyles filled with television, video games, and computer screens. But more and more, studies show that children need “rough and tumble” outdoor play in order to develop their sensory, motor, and executive functions. Disturbingly, a lack of movement has been shown to lead to a number of health and cognitive difficulties, such as attention deficit/hyperactivity disorder (ADHD), emotion regulation and sensory processing issues, and aggressiveness at school recess break. So, how can you ensure your child is fully engaging their body, mind, and all of their senses?
Today it is rare to find children rolling down hills, climbing trees, or spinning in circles just for fun. We’ve taken away merry-go-rounds, shortened the length of swings, and done away with teeter-totters to keep children safe. Children have fewer opportunities for unstructured outdoor play than ever before, and recess times at school are shrinking due to demanding educational environments.'
I work with preschoolers and their parents, and I see so many parents who don't** spend more than a few minutes a day outside, who stop their kids get messy, or interrupt their play. The art of play has become lost and replaced with plastic toys, screens and adult led games, where the priority is the washing pile. It makes me want to scream!
I really have to work with encouraging parents to sit back and leave the kids to it.
My four kids all have differing levels of tolerance and they all explore according to their own interests. It all comes together in the end. We don't have our own washing machine.
YABVVVU.