"I found an incredible joy and levity in his books, and that surprised me," Guggenheim tells A.frame. "At first, I thought, 'Someone should direct a movie about Michael,' and then I realized, 'No, I should direct a movie about Michael.'"

That movie is Still: A Michael J. Fox Movie, which features intensely personal interviews between Fox and Guggenheim about the former's life and legacy, as well as exploring the ways in which the actor has dealt with his diagnosis of early-onset Parkinson’s disease. According to Guggenheim, it was Fox's resilient spirit in the face of adversity that struck such a chord with him. "It made me think, 'If this guy can be so upbeat when he's got this chronic diagnosis and I'm more dark and pessimistic than him, what's really going on here?' I wanted to solve that riddle," he recalls.

"The best movies, for me, are the ones that you come at personally," says the filmmaker. "I just felt drawn to Michael as a person."

A.frame: Michael J. Fox is somebody who has been a constant fixture in a lot of peoples' lives for 40 years. Was the thought of exploring his career and pop cultural impact onscreen at all daunting, or just exciting?

It's always a little daunting, but mostly exciting. I wanted to break out of the sort of rut I was in. I mean, it was a good rut. I had made a lot of films that are about substantial things and topics that stimulated my intellect. But I wanted to break out of that, and there's something about Michael that was appealing to me. "Appealing" doesn’t even seem like the right word. There's something about him that I needed.

The film really captures his resiliency. There's a moment near the start of the film where he falls and this woman comes back to check on him and he just looks at her and quips, "You knocked me off my feet."

He's a saint. That could easily be a line from Alex P. Keaton or Marty McFly, and that moment says a lot. It was a total surprise, first of all. We almost cut just before that. We thought the take was over and he trips very deep in the frame. I've watched it so many times, though, and the thing is that he's being very deliberate with his steps while he's walking so that he doesn't fall, and then the thing that trips him up is the woman. They pass each other and she says, "Hello, Mr. Fox," and he can't help but turn to face her because he's that kind of guy. He doesn't want to be aloof. He wants to be kind, and it's that kindness that sends him tumbling. And then, of course, instead of doing what I would probably do — which is stay on the ground and call my family — he gets up and says, "You knocked me off my feet," and the woman laughs. It says everything about him. He insists that no one looks at him like he's a pathetic creature.

You use a blend of multiple different kinds of footage and media in the film. What was your thought process behind shooting some of the recreation footage used in the doc?

I knew we had to do recreations right away. Then we got Michael Harte to come on board as our editor, who's a genius. I think at Sundance I called him a "wizard genius," and I genuinely do believe that, because he's just the most gifted editor. My solution to depicting certain moments that we didn't have any archival footage for was to do recreations. His solution was always to try and find moments from Michael J. Fox's movies and re-craft them in new and inventive ways. I've seen that done before here and there. Ethan Hawke does it in his Paul Newman and Joanne Woodward documentary series, The Last Movie Stars, which is wonderful. But Michael does it very differently in Still.

You mean because he blends the recreations and movie scenes together?

Yes. For instance, it goes by too fast because it's at the very beginning of this movie, but there's a shot of this hotel in Florida. It's the first shot of the film. Then we cut to a hallway and then to a bed and then you see this figure in the bed and the figure turns and that's all recreation. But then when we cut to a close-up of him waking up, that's from The Secret of My Success. Then we cut back to the hotel room and we show him having a fistfight with Woody Harrelson in basically 10 different movies. In those scenes, the editor and I always battle a little about how to depict each moment, and we fought and fought and fought until the movie decided what was best, ultimately.

Michael is really the only person directly interviewed in the film. Did you ever consider including interviews with any of his peers or family members?

I almost didn't interview him, actually. The original plan was no interviews at all. I pitched the film to Apple that watching it would feel like watching an '80s movie. I wanted a big score. I wanted big music cues from Guns N' Roses and the Beastie Boys. I even got John Powell to score the film, and he'd never scored a documentary before. He's just done big Hollywood movies previously. I so wanted to switch directions from my previous films. I wanted to take people on a wild ride, and interviews tend to slow films down. Interviews are like the basic language of documentaries. But I'd been working on the film for a while already, and I was doing this commercial and this cinematographer showed me a shot where you can put the camera in a certain way that it looks like the interviewee is looking into the lens. It worked really well, but you have to sit really close to the camera in order to achieve that effect.

So, Michael and I were always only about four feet apart from each other. We were always looking right into each other's eyes, and I just thought, "This is amazing." It was so right, because he's right there. I didn't know for sure if it was going to work or if the audience would always be able to understand him — because sometimes his Parkinson's makes it difficult to understand what he’s saying — but he was so funny. He's funny exactly the way you see he is in the film, and he's so winning that it just worked. So, we did more interviews. We just kept going back. We did that kind of interview together about six different times.

Fox does the most ambitious work of his career in Brian De Palma's take on the Vietnam War. He plays a private who dares to go against a gung-ho sergeant (Sean Penn) after the rape and murder of a civilian. The film never got the attention it deserved, in part because it premiered in the shadow of "Platoon." HBO Max