The 65-year-old Canadian-American actor was diagnosed with young-onset Parkinson's disease a year after Back To The Future Part III, in which he played the character Marty McFly, was released in 1990.
Fox told The Hollywood Reporter: "It's (acting) really prolonged my life and made my life interesting in a way that I didn't think it would be to this point, I'm not retired from acting, but if I didn't act again, it would be for a very good reason. I let Parkinson's make decisions for me."
The actor went on to say that he had to overcome "vanity" when revealing the impact the disease had on him, and added that he needed to "normalise it".
Fox said following his revelation, he would anonymously enter chat rooms featuring Parkinson's patients and ask what they thought of the celebrity, meaning himself, who had just gone public.
He said the responses would range from encouraged to ecstatic, and the actor explained: "I thought, 'well, f*** you, I have Parkinson's and you're celebrating'."
Fox first noticed a tremor in his little finger before his diagnosis aged 29 and the progressive neurological condition has severely affected his mobility.Â
He has suffered broken bones from numerous falls.
Fox has previously been open about how the disease affected his memory and made it difficult to remember dialogue in his acting roles.
He founded the Michael J Fox Foundation for Parkinson's Research in 2000, which has raised more than $US2 billion ($A2.9 billion).
In 2023, he starred in the Apple+ documentary Still: A Michael J Fox Movie, exploring how Parkinson's impacted his life.
As well as starring in the Back To The Future trilogy, Fox is known for films including Teen Wolf and Doc Hollywood along, and the TV series Spin City.
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