Former San Francisco 49ers wide receiver Dwight Clark announced he's battling ALS. 

60-year-old Clark was diagnosed with the degenerative nerve disease after feeling weakness in his left hand back in September 2015. Clark suspects his case was caused by football, but says he doesn't know that for sure. 

Since being diagnosed, the disease has left him with weakness in both hands, his lower back and right leg. He says he can no longer run, play golf or walk any significant distance. 

Though there is no cure for ALS, Clark vows he'll "fight like hell and live every day to the fullest." Clark played for the 49ers from 1979 to 1987 after being drafted in the 10th round out of Clemson. 

Dwight is best known for catching the game winning touchdown pass in the 1981 NFC Championship Game in a play that became immortalized simply as "The Catch."