"I want people to understand just how quickly ALS can attack your body," he said.
"I can't even hold a cup if I try, and that's despite being diagnosed relatively early."
By sharing his story, Johnson hopes to accelerate diagnosis for others and push for better treatments. "That's why early detection, more research, and better treatments are so important.
We have to give people a better chance than what's available today," he said.
Johnson emphasized that while his physical abilities have declined, his mind and emotions remain unchanged. "I still think the same.
I still dream. I still love my family," he said.
Johnson retired after the 2017 season, having also played for the New York Jets and Arizona Cardinals.
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He led the NFL with 2,006 rushing yards in 2009 and set a league record with 2,509 yards from scrimmage that season.
