Jimmy Johnson Says "Survivor" Experience Was Tougher than Football Training

MIAMI (CBS/AP) Is "Survivor" tougher than professional football? Ex-NFL coach-turned-reality-show contestant, Jimmy Johnson sure thinks so. 

PICTURES: "Survivor: Nicaragua"

Johnson, who spent more than a month in Nicaragua this summer with "Survivor" as one of the 20 castaways vying for a million dollars, said competing on the reality show was tougher than three-a-days.

Speaking by phone from his home in the Florida Keys, Johnson calls the experience a "great adventure, but it was at times miserable."

At 67, Johnson, who is known as much for his well-kept locks as he is for his wins, is the oldest contestant competing on the show, which this year is split into two teams: OId vs. Young.

No stranger to competition, Johnson is the former coach of the Dallas Cowboys, Miami Dolphins and Miami Hurricanes.  He is now part of the Fox NFL broadcast team.

Host Jeff Probst revealed that Johnson, a big fan of the show, tried to get on the series in the past.

"He's applied two other times," Probst said, "and got turned down both times because of medical issues. ... Last year when he applied ... they found a problem with his heart. ... He believes 'Survivor' was in his life for a reason, that it saved his life, and now he's hopes he can kick its ass and win."

The 21st installment of "Survivor" is set to premiere on Sept. 15.