Fox was diagnosed with Parkinson's disease at just 29 years old
When Fox noticed that he had a twitch in his pinkie finger, he originally thought that it was from him getting hurt while doing stunts for his movie. But, when he was just 29 years old, the doctors told him that he had Parkinson's disease, which is an incurable neurodegenerative disease of the central nervous system.
At first, Fox did not share this news outside of his family and close friends, and while his family managed to handle it, Fox fell into a deep depression and began to drink heavily and act erratically. Fox learned that drinking would do nothing for him, so he stopped and decided to try therapy. He realized that he "had no choice but to take life one day at a time."
Photo source: Michael J. Fox and Tracy Pollan by Alan Light