“There is a time for everything, and my time of putting in a 12-hour workday, and memorizing seven pages of dialogue, is best behind me,” the Canadian-American actor, 59, revealed in his new book and fourth memoir, “No Time Like the Future: An Optimist Considers Mortality.”

“At least for now … I enter a second retirement,” the “Family Ties” star continued. “That could change, because everything changes. But if this is the end of my acting career, so be it.”

The decision follows Fox, who was diagnosed with Parkinson’s disease at 29, recently noticing symptoms of the disease including memory loss, delusions and dementia, cognitive declines which he writes he had “rarely contemplated before now, much less spoke of.”

These have included confusing his twin daughters and searching for his car keys — despite the fact that he can no longer drive.

The “Back to the Future” star also suffered a bad fall in 2019 while filming a cameo for the movie “See You Yesterday,” just four months after undergoing surgery to remove a tumor on his spine.

Fox credits his optimism for allowing his career to continue despite his physical degradation. When he was diagnosed with Parkinson’s in 1991, a doctor told him he’d be lucky if he was able to work another decade, a prediction which, 30 years, seven Emmy nominations and one Emmy win later, Fox has clearly defied.

In addition to discussing his health and future career, Fox also touches on his family, famous friends and sobriety struggles in his book, out this week.

“She’s not always a rock, but that’s okay,” he writes of wife Tracy Pollan, to whom he’s been married for 32 years. “Rocks are solid, stubborn, and immovable. That’s me. Tracy, on the other hand, has learned to keep the rock rolling.”