Go outside and play.

When I grew up life after school was simply "Go outside and play, and be home for dinner."  There are SO many health benefits to simply going outside besides the obvious natural exercise.  You are exposed to Vitamin D from the sunlight on your bare skin, and getting dirty exposes your microbiome to critical beneficial bacteria for your gut.  Creative play and socialization with friends is extremely important for the developing mind, planning skills and discovering the art of negotiation.  Socialization is a critical key to happiness.  Spending time with others whether it's playing in the sandbox at two, enjoying a cup of coffee with a friend or rocking on the front porch at 90, is the key to longevity.  I remember climbing pine trees with my next door neighbor many, many days when I was in elementary school.  We would shinny up these pines that weren't that big, maybe six inches diameter, and climb way up until the tree swayed in the light breeze,... bracing ourselves on a branch, hooking an arm around the trunk, laughing and talking.  An hour later we would scramble down, run around a little and climb two more trees.  Yes, we might come home scratched, dirty, sticky with pitch and bruised - but it was all good!
 
Have discussions with your children's caretakers and their friend's parents and express your preference for active play instead of hours of screen time.  Allow your children to figure out creative play themselves.  Send them outdoors, even if it's mud season, and let them get sweaty and dirty.  And think about joining them!  Shoot hoops for 15 minutes with your kids, start planning and dig a vegetable garden,... keep the television off, turn the music on and you may find yourself dancing while you cook or clean!  Most importantly, be an example to your children and their friends.  For ways to reduce screen time in your home and increase activities and socialization read this post.