"In… Out… In… Out…" I chant like a warm, motherly boot camp instructor.

"Eve, move your legs."

"You can’t stop, London. In… Out… In…"

They look at me with blank faces. Eve kicks her feet out giddily but forgets to pull them in. When she does, it’s too late, and the sudden movement jerks her out of rhythm. 

London hardly tries, her feet more dangling than pumping.

I hop on the black seat beside London’s and begin modeling the main principles of swinging. I push my feet out and lean back, toes pointed to the sky, hair trailing behind me. At the top of the swing, seconds before the chains jerk, I thrust my torso forward and pull my legs in tight, under my seat. Again, just as the swing hits its highest point, I switch. Over and over I alternate between curling and extending, between constricting and expanding, between confinement and freedom.

"In… Out…" I sing.