Meredith Baxter recalls working with Michael J. Fox on "Family Ties" and watching his star rise as the show went on.

Michael J. Fox is sharing details about the early days of his career and how challenging it was to balance playing two iconic characters.

In his new memoir, "Future Boy," the actor opened up about the difficulties of balancing the filming of the third season of his hit sitcom, "Family Ties," with 1985's "Back to the Future."

"Time definitely went rogue in the late winter and early spring of 1985, and took me with it," he wrote. "During three long months, I was Alex, I was Marty, and I was Mike. That's two too many. In order to complete my work, at least one of them had to go, and Mike was the odd man out."

He later added, "I was Alex P. Keaton during the day, and Marty McFly at night. The twenty-hour workdays left little time to be me, Mike Fox."

MICHAEL J. FOX MADE 'BACK TO THE FUTURE' CO-STAR FEEL LIKE SHE 'HAD A HIGH SCHOOL BOYFRIEND'

Fox detailed what a typical week filming both projects was like - one example involved waking up at 7 a.m. and receiving a script for "Family Ties," and going through an entire day of rehearsal, which ended at 6 p.m.

Immediately following the rehearsal, Fox was on his way to Universal to continue filming well into the night, writing he didn't finish until 3 a.m. Despite the long night of shooting, Fox was up the next morning at 7 a.m. once again.

"During three long months, I was Alex, I was Marty, and I was Mike. That's two too many. In order to complete my work, at least one of them had to go, and Mike was the odd man out."

-- Michael J. Fox

"By 3:00 a.m., I'm passed out in the backseat of the station wagon," he wrote. "My teamster driver practically carries me into my apartment and deposits me in my bed, my alarm set for four hours of sleep."

Fox shot to stardom playing Alex Keaton, the conservative son of two liberal parents, on "Family Ties," which he starred in from 1982 to 1989. The show also starred Justine Bateman, Tina Yothers, Meredith Baxter and Michael Gross.

He then achieved an even higher level of fame when "Back to the Future" and its subsequent sequels were released.

While it was difficult for him to juggle both roles at once, Fox wrote, "it was business as usual" for the rest of the "Family Ties" cast.

He wrote, "I recently asked Justine Bateman about our work together during that period. 'The remarkable thing is,' she reflects, 'I didn't notice anything. I knew you were doing the movie, and I just remember being confused about when any sleep was occurring. You do the math -- I don't know, he's putting a full day there at night and then coming here. I don't get where the sleep fits in. I felt like, well, if anybody can do that kind of thing, it's Mike.'"

Unbeknownst to Fox, there were many people looking out for him during the filming of "Back to the Future."

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When speaking with the film's assistant director, David McGiffert, for the book, he learned that the A.D. "had to put my foot down with Bob" after he found out that director Bob Zemeckis had a dangerous stunt in mind for Fox.

"He wanted you to be on the skateboard in front of the car, which would be pushing you," McGiffert said in the book. "He had a certain angle in mind that only worked if you were the one doing the bit, so he said, 'Yeah, I want Michael to do it.' I shook my head. 'Bob, he can't do that. You can't have your lead actor in that position. I know it's an off chance, but if he falls under the car, it's over in a heartbeat.'"

Despite his arguments against it, McGiffert said Zemeckis continued to insist Fox be the one to complete the stunt. It wasn't until McGiffert threatened "to put a note on the slate that says 'First AD protests'" that Zemeckis changed his mind and allowed a stunt double to film it instead.

The dangerous stunts didn't stop there, as Fox previously opened up about a stunt which went wrong on set of "Back to the Future III," in his first book, "Lucky Man: A Memoir." The stunt involved Fox being dragged through the streets by horses before Christopher Lloyd's character arrives to save him.

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"This worked well for the next couple of takes," Fox wrote, "but on the third I miscalculated the positioning of my hand. Noose around my neck, dangling from the gallows pole, my carotid artery was blocked, causing me briefly to pass out."

He continued: "I swung, unconscious, at the end of the rope for several seconds before Bob Zemeckis, fan of mine though he was, realized even I wasn't that good an actor."

Michael J. Fox recalls '20-hour days' that nearly broke him filming 'Back to the Future' and 'Family Ties'