Of course, months of preparation went into the movie before a single frame was shot. "Will and I … went to the CDC and to the University of San Francisco and met some virus hunters to see what it's like to be a virologist and how they think," says Lawrence, who first met Smith when he directed the actor-rapper's "Black Suits Coming" video for "Men in Black II."
Other expert sources, like a psychiatrist who deals with people in isolation and solitary confinement, helped them understand the psychology of a solitary existence. Smith and Goldsman also interviewed an ex-prisoner who'd spent time in solitary. "The one thing that was across the board was schedule," Smith says. "He would schedule things like cleaning [his] nails. That was the only way to maintain sanity."
Working out was part of Neville's regimen, and thus Smith's. He lost 20 pounds and gained a six-pack by running five miles a day, six days a week. "What we determined from our research is that eating becomes just something that you do just because you have to," he says. "There's no pleasure, there's no real desire to eat. You just know that your brain won't function if you don't."
Smith's onscreen internal monologues -- sometimes in the form of having a conversation with himself, his dog or a mannequin -- were more of a challenge. "It's a weird thing you have to do, but when you see it, it looks like there's a lot going on even though it's a dude sitting there with a dog," Smith says.
"There aren't many actors that can pull off a one-man show," says Lawrence. "Part of it is just his charisma. Part of it is he's a really good actor. He's very precise with his choices, which is very important for this movie because there's so little dialogue."
Smith relished the challenge, but can't imagine actually living in Neville's shoes. "As much as people get on your nerves on the freeway," he says, "as much as people irritate you in your daily life, if you took everyone away, it would be the most miserable existence that you could experience. There was absolutely no pleasure for me at all in experiencing that amount of loneliness and solitude."
But without giving too much away, in the end there is a ray of light to redeem the darkness. "It's a movie about hope and the struggle to find hope in the face of so much loss," Lawrence says. "It's a very simple, human idea."
To learn more about "I Am Legend" and movie special effects, check out the links on the next page.