Chris Johnson, a former NFL running back, reveals he has a rapidly progressive, sporadic ALS diagnosis and now communicates with an eye-controlled speech device.Johnson says he was diagnosed last year at 39 after noticing weakness in his right hand and that the disease has robbed him of basic strength while leaving his mind clear.He appears on "Good Morning America" with Michael Strahan and his wife Brittany Johnson to describe his treatment plan, which combines three medications and other therapies, and to praise experimental clinical trials.Johnson says he is sharing his story to raise awareness, encourage earlier diagnosis, and press for more research funding while continuing advocacy and fundraising despite his limitations.