This I didn't know:
But although the online videos of men scaling drainage pipes and jumping from rooftop to rooftop make [parkour] seem like the latest extreme sport, its metaphysical component makes it more of a nascent martial art. Freerunning focuses on the feeling and aesthetic expression of freedom, thinking that can be traced to the transcendentalism of Rousseau and Thoreau. And parkour's "utility," of which Mr. Cliff and other traceurs speak, is akin to the Utilitarianism of John Stuart Mill and Jeremy Bentham in its application of mathematical principles to everyday life.
I can just see Mill trying this, can't you?
Apologies for random beefcake.