Properly speaking, of course, there is no such thing as a return to nature, because there is no such thing as a departure from it. The phrase reminds one of the slightly intoxicated gentleman who gets up in his own dining room and declares firmly that he must be getting home.
Chris would use the spiritual aspect to try to motivate us. "He'd tell us to think about all the evil in the world, all the hatred, and imagine ourselves running against the forces of darkness, the evil wall that was trying to keep us from running our best. He believed that doing well was all mental, a simple matter of harnessing whatever energy was available.