Michael J. Fox remembers how it took him a couple days to build up the courage to return a voicemail left by Muhammad Ali.
Even after he was finally prepared to call back one of the most famous men on Earth, Fox said he ran into a bathroom so nothing would distract him.
"It took me a couple of days to return the call because I just, he's such a hero of mine, I didn't know what I would possibly have to say to him," Fox told NBC10 in an interview Saturday afternoon while visiting the Wizard World convention in Center City. "So I took the call in my bathroom because I wanted some privacy. And I had three kids running around at the time. I didn't want any distractions."
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The conversation happened shortly after Fox was diagnosed with Parkinson's disease, an incurable, degenerative illness, in the early 1990s. Ali had been diagnosed nearly a decade earlier in 1984.
Fox said Ali's words on that phone call became a "formative moment in my life."
"I got on the phone with him and he was quiet for a while, and then he said in a very soft voice, 'I'm glad you're in this fight with me,'" Fox said.
The conversation also proved pivotal for thousands of people suffering from Parkinson's and the public fight to ease their pain — and find a cure.
The last transformative moment in Ali's legendary life came about the same time as that conversation when in 1996, the retired boxer lit the torch at the Olympics in Atlanta.
Fox announced his Parkinson's affliction publicly two years later in 1998, and while the two did work together to raise awareness, the "Back to the Future" star took the mantle as the public face for the disease over the last two decades.
"Fighting in Congress with him was an amazing experience," Fox said. "He didn't have that ability to communicate very well, so he had somebody read his words. But he knew it was his belief and his ambitions that were being represented."