-- ELI PARISER is founder of Upworthy.com, former executive director of MoveOn.org, and author of the bestselling book "The Filter Bubble". He talks about what it takes to make meaningful content go viral... and what he says to critics who call Upworthy manipulative clickbait.
-- Canadian ultra-marathoner and philanthropist RAY ZAHAB has run across the Sahara, the Gobi Desert and has plans to do an unassisted run across Baffin Island, in Canada's far north. He discusses the limits of human endurance and what drives him to keep on pushing himself.