[SetTheorist]

The original quote is a bit unclear, but it does refer to being on a playground:

"Recall the pure joy of riding on a backyard swing: an easy cycle of motion, the momentum coming from the swing itself. The swing carries us; we do not force it. We pump our legs to drive our arc higher, but gravity does most of the work. We are not so much swinging as being swung."

[ricardobeat]

It's a bit confusing since it starts with "Rowers have a word for this frictionless state..."

I spent a good minute or two trying to picture what 'drive our arc higher' could mean during rowing, as that is not when force is exerted...