01:57Former NFL star Chris Johnson has revealed he has been diagnosed with ALS during a heartbreaking TV appearance.During an interview with Good Morning America on Monday (29 June), the three-time Pro Bowler said that he was first diagnosed with the disease last year, at the age of 39.“There’s no history of ALS in my family,” said Johnson, whose first symptom of the disease came about as a weakness in my hand.He said that after watching an interview with Eric Dane, who died from the disease in February, he reached out to Dane’s doctor at the time, Dr Merit Cudkowicz, who is now helping him with “experimental treatment”.“We've been with her ever since, and that changed the course of our fight."Up next