By Mark Dagostino
December 08, 2008 12:00 PM

As he took the stage in Manhattan Nov. 5, Michael J. Fox was all smiles: He was about to play guitar with The Who. “This is almost worth getting Parkinson’s for!” he shouted into the mic as the band kicked out the opening chords of “Magic Bus.” It was the grand finale of this year’s fund-raising dinner for the Michael J. Fox Foundation for Parkinson’s Research. And as the music peaked, Fox—flanked by rock legends Pete Townshend and Roger Daltrey—swung his right arm in a giant circle, striking the strings with the windmill move that Townshend himself made famous.

The crowd went wild. It was a triumphant moment—for more than one reason. “My whole mission during dinner was to time [my medication] so when I got up with The Who I could actually play,” says Fox. “Because if I mistimed that, there’s a chance I’d get up there and not be able to move my arms at all.”

Ten years after revealing in PEOPLE magazine that he was struggling with Parkinson’s disease, Fox, 47, still seems like the optimistic, energetic guy America fell in love with in Family Ties and Back to the Future. But the inescapable reality is that his disease is progressing. Fox can lapse into a condition that doctors call “bradykinesia,” in which his arms hang heavy by his sides. At his worst, his voice is barely audible, his speech is slurred, and his face is almost void of emotion. Even though he takes a specific cocktail of prescribed drugs, Fox says, he suffers that state “at some point every day.” And any number of variables can make his condition worse. “It can be affected by whether or not I’ve eaten enough protein, or if there’s a low-pressure system in the weather,” Fox says. “If it’s cloudy outside, I can feel it.”

But save any sympathy—because Fox certainly doesn’t feel sorry for himself. “I refuse to define it in terms of a hardship or a difficulty,” he says of Parkinson’s effects. Timing his medications, which must be administered every couple of hours, consumes his time and energy, but Fox is pragmatic. “If you don’t want your feet to get wet, you wear shoes,” he says. “It is what it is. You either get Zen with this [stuff] or you lose your mind.” Having Parkinson’s “is part of an amazing life. And not an ‘otherwise’ amazing life,” he clarifies. “It’s part of what makes my life amazing.”

Sitting on a worn sofa in his home office near Manhattan’s Central Park, Fox talks about how that life revolves around his wife, Tracy Pollan, and their four children: Sam, now 19 and a freshman science major at college; twin 13-year-old daughters Aquinnah, the ballet dancer, and Schuyler, the athlete; and Esmé, 7, who “could be anything from an actress to the President,” Fox says, marveling at how his youngest turned a recent ordinary Monday night at home into a candle-lit Princess Ball just for him. Now that Sam is living away at school, “the estrogen levels are way out of whack” in his house, Fox says, laughing. “Even the dog’s a girl!”

When he’s not at parent-teacher conferences or taking the whole gang to the country to see their grandparents on weekends, much of Fox’s time is spent in this room, where for months he’s been working on his next book, a memoir of the last eight years called Always Looking Up, due out in April 2009. The acting world has beckoned lately too: In addition to promoting a new DVD release of Spin City, he recently shot a guest-starring role on pal Denis Leary’s FX show Rescue Me. When he needs a break, he pulls out one of the electric guitars he keeps in his office: “I turn satellite radio to the ’60s stuff and play whatever comes up. I can do that for hours—until my pills wear off.”

As he sat for an interview with PEOPLE, Fox had to wait a good 10 minutes for his pill to kick in—a pill that helps control his dyskinesia, the spastic movements that now occur as a side-effect of the drugs that make it possible for him to move at all. After years of tremors and body contortions, “I get a lot of joint and foot pain,” he says. But Fox is “grateful” that his Parkinson’s hasn’t been accompanied by clinical depression—as many cases are. Though his kids feel protective of him—Pollan says that when the family goes to restaurants, for example, the children make sure their father sits where he’s most comfortable—”Our family life is so normal,” says Fox. His kids “don’t see me as suffering from anything. The joke is, we’ll be going to school and I’ll say, ‘Choose to have a great day!’ and they’ll roll their eyes at me. They see me as positive, upbeat.” Most days, he says, “Parkinson’s doesn’t even come up.”

Fox’s battle with the disease began in 1991, when he noticed a “twitch” in his left pinkie while filming the romantic comedy Doc Hollywood in Florida. Six months later, a doctor in New York made the grim diagnosis. Fox dealt privately with Parkinson’s for the next seven years; at first, despair over his condition lead to bouts of heavy drinking. “I craved alcohol as a direct response to the need I felt to escape my situation,” he wrote in his 2002 memoir Lucky Man.

Frightened by thoughts of where his “joyless” addiction was leading, Fox got sober in 1992 and welcomed his twins three years later. But he continued to keep quiet about the Parkinson’s, even during his return to TV on Spin City in 1996 and through a radical brain surgery which greatly reduced the tremors on his left side in March 1997.

But the following year, Fox decided he could no longer hide. “It’s not that I had a deep, dark secret,” Fox told PEOPLE at the time, explaining that the secrecy became heavier to carry than the disease itself. “I think I can help people by talking,” he said. “I want to help myself and my family.”

His wife admits today that she wasn’t so sure: “Michael’s private, but I think I’m even more so,” says Pollan, 48. To her delight, “it turned out to be a very positive thing.”

The outpouring of public support after PEOPLE’s cover was “much more than I expected or deserved,” Fox says. Realizing that he could affect the fight for a cure, Fox went before Congress in 1999 and asked for more federal funding for research. And in May of 2000, when he left Spin City to spend more time with his family, Fox established the Michael J. Fox Foundation for Parkinson’s Research (see box).

Fox’s own doctor Susan Bressman, Chair of the Department of Neurology at New York’s Beth Israel Medical Center, is optimistic about what lies ahead. “Michael’s doing terrifically well,” she says. “He copes so beautifully and he’s such an optimist that he’s a role model for everybody—whether you have a disease or you don’t.” Though new surgical techniques have been developed since Fox last went under the knife, the star isn’t interested. “The next time they’re going into my brain, they’re going in with the goods to get it done. If they can’t do that, then I’m not ready,” he says.

If Parkinson’s impedes anything in Fox’s life now, it’s spontaneity. “If I want to take Esmé to school and I have 10 minutes, I don’t know for sure within that 10 minutes if I’ll be able to put my shoes on to go out the door,” he says. “But it’s little stuff.” In recent years, he had to give up running, but he can still drive a car and ice skate: “I’ve been playing hockey for the last 10 years!” he says proudly. “Tracy has this joke with me. I’ll say, ‘I can’t do this anymore ’cause of [Parkinson’s],’ and she’ll go, ‘No, you can’t do that anymore ’cause you’re old!'” After 20 years of marriage, Pollan says, “emotionally, we’re closer than ever.”

Over the past decade, he and Pollan “haven’t looked back. For everything that’s worse, there’s something that’s better,” he says, citing the increased time he’s gotten to spend with his family as “a tremendous gift. That’s been incredible. I really love my life. That’s just me. I understand Parkinson’s is a real hardship for [some] people, and I’m not trying to be insensitive to them. But I have to be realistic about my situation. Yes, it’s a horrible condition. Would I choose not to have it? Yeah, I think so. But it’s not my choice.” If it weren’t for Parkinson’s, Fox says, “I never would have written books, or met the people I’ve met or traveled to the places I’ve traveled.”

Even when his thoughts turn to the future—and the fact that finding a cure may take much longer than the 10 years his foundation initially hoped—Fox says he isn’t concerned about the end stages of Parkinson’s. “I’m almost sure that in 10 or 12 years we’ll have much better medication for it,” he says. “Based on how I feel now, I’ll be okay for at least 10 more years.” So what does “okay” mean to Michael J. Fox? “Living a life,” he says, “that’s not much different than what I live now.”