Do you see how the snippet makes sense with the expansions closed—we don't need that detail to be able to follow the main action.
But the expanded detail adds more richness and life to the story—it puts us in the scene. Otherwise the story would be meh—they ran, they ran some more... so what?
So to write your own variation, you need two key actions with expanded detail.
But what kind of detail? Take a closer look at the environmental details inside the expansions.