Kirby reminisces fondly about her mom being the only parent who got out and played with the neighborhood kids. Kirby followed in her footsteps. The kids noticed. "You like being with us!"
Outdoor play can be for parents and children. It's really important to play outside with kids, not just to send them out and invite neighborhood kids over. Their development will leap ahead -- socially, cognitively, physically, relationally (especially toward the parent playing with them).
But you may not have had an experience like Kirby's. And if you have not seen it modeled, you may not be able to picture it.