Comment on How Tough Mudders and 'Ninja Warrior' turned primal fears into big business

"It takes a special breed of person," said Janice "JJ" McClean as she watched veterans of NBC's popular obstacle course show "American Ninja Warrior" and "Ninja" hopefuls scale a 14-foot-3-inch warped wall, an intimidating concave structure that mimics one on the show. Then they took turns walking tightrope-style across a slackline - essentially a strap tied to two poles.