The man pulls the buttoned blue shirt down over his head and waits. His hands, bony, cratered, have lost their strength, so the shirt flutters open at the sleeves and neck. His wife walks into the bedroom. She takes his left hand in hers, and closes the button around his wrist.

“I did succeed in shaving this morning,” says the man.

“Without cutting yourself?” says his wife.

“Without cutting myself.”

The man built so much of this city. Look around. The World Trade Center, rebuilt from a mangled hole in the ground? He led that. The High Line and Hudson Yards? He led those, too. Barclays Center, Citi Field and the new Yankees Stadium? Parks on Governors Island and the Brooklyn waterfront? The East River skyline from Williamsburg to Long Island City? Him, him, him.

Once, and it wasn’t so long ago, Dan Doctoroff had more power to decide what got built in New York City than anyone since Robert Moses. Now he is diagnosed with A.L.S., a neurodegenerative disease also known as Lou Gehrig’s that attacks the motor neurons in the brain and spinal cord, causing patients to lose control of their voluntary muscles. A.L.S. turns the body into a prison. Only the eyes and brain remain mostly unaffected. Death comes by lung failure and suffocation, usually within three to five years of diagnosis.

Mr. Doctoroff is 65. He was diagnosed almost two years ago.

As a powerful man loses authority over his own body, how does he change? And what remains?

It is winter, 2005,

and Mr. Doctoroff is thinking ahead, to a summer day seven years in the future. He is deputy mayor of New York, charged with rebuilding the city after 9/11. His job is to dream the future, and then to marshal the city’s gargantuan bureaucracy to get those dreams built. His boss, Mayor Michael Bloomberg, has even compared Mr. Doctoroff to Mr. Moses: both master builders, both at once respected and resented for their relentlessness and their impatience.

But even Mr. Moses never tried to bring the Olympics to New York.

Mr. Doctoroff visits corporate suites, hotel conference rooms and newspaper editorial boards to give his pitch. In his mind, the 2012 Olympics are already about to start. Ferries cross the East River in a parade. The boats carry athletes to a gleaming Olympic Village, built in Queens atop the ruins of empty warehouses and falling-down piers.

Come, he says. Dream with me.

How many times has Mr. Doctoroff given this spiel? A hundred? As he repeats it, he worries. He feels trapped between his imagined future and the onrushing now. His mind jumps again, to the six emergencies erupting across his desk. He feels pulled in so many directions, it’s hard to be present with people. Do they notice?

He’s right to worry. People notice. A journalist who hears the Olympics pitch describes Mr. Doctoroff as a man whose eyes “gaze past you, out towards the horizon.”

Why this constant drive? Why does he find it so difficult to be present? For years, he doesn’t know. His brother Andy says Mr. Doctoroff should be more introspective, and who knows. Maybe Andy is right. Mr. Doctoroff is aware that he graduated Harvard aimless and lazy. Wound up in New York by following his wife, Alisa, who got a job in town. Bluffed his way into a job on Wall Street. Discovered he enjoys spinning numbers into stories, stories with grand ambitions, like a highly leveraged company with hidden potential, or why New York must host the Olympics.

“You could tell he’s very bright, and very competitive,” recalls Stephen Ross, founder and chairman of the real estate development firm Related Companies, who heard the pitch, dropped his own Olympic bid and joined Mr. Doctoroff’s team.

It is hard work seeing the future, and so Mr. Doctoroff puts everything into the job. But peering into the future makes it hard to see the present — hard to be home with his wife and children, hard to really see them. He leaves his townhouse on the Upper West Side each morning in darkness. He rides his bike down the Hudson River trail. He arrives at City Hall before sunrise, even in summer. He starts dozens of development projects, from the Bronx to Staten Island. He flies around the world, advancing the Olympics bid. He runs on discipline and work and depths of ambition that seem — even to his very successful friends — a little freakish.

His staff, mostly Ivy League types 20 years his junior, try to keep up. They fail.

“‘Don’t tell me no. I don’t believe in no,’” Sharon Greenberger, Mr. Doctoroff’s first chief of staff in city government, says of his worldview back then. “Barriers are temporary. And we just keep going.”

At city hall, no project goes smoothly. Each elicits an angry petition, a news conference, a lawsuit from neighbors or a state senator. Assembly Speaker Sheldon Silver kills Mr. Doctoroff’s plan for a stadium on the west side of Manhattan, and with it the entire Olympics bid. Governor George Pataki and leaders at the Port Authority rebuild the World Trade Center with office towers, overruling Mr. Doctoroff’s push for a mixed-use neighborhood of apartments and restaurants. Apartment towers and a basketball arena rise in Downtown Brooklyn, but local residents and the 2008 recession force developers to abandon Mr. Doctoroff’s larger plan for 17 high-rises, many up to 50 stories tall.

Mr. Doctoroff’s impatience grows. Ms. Greenberger invents the Doctoroff Mood-o-Meter, advising staff whether to approach or hide. Mr. Doctoroff’s tantrums cause Mr. Bloomberg so much joy, the mayor stops working, eats popcorn and watches.

“Dan’s team at City Hall was very familiar with his impatience and demanding style,” Mr. Bloomberg says of those days in an email, “but they would have run through a brick wall for him.”

Opponents accuse Mr. Doctoroff of “unmitigated arrogance,” according to an editorial in The New York Post. So do allies, including Senator Chuck Schumer.

“He was a bulldozer,” Daniel Goldstein, the leader of a group of neighbors fighting Mr. Doctoroff’s plans for Downtown Brooklyn, tells The Village Voice.

“I just think I was a little out of control,” Mr. Doctoroff says. “I was jet-lagged constantly, probably in a bad mood, which is why sometimes I would yell at people. Which I regret.”

Only Mr. Doctoroff’s closest aides know his mother is fighting cancer. Then his father is diagnosed with A.L.S. Every three weeks for eight years, Mr. Doctoroff travels to his hometown near Detroit, first to care for his mother, then for his father. Both parents die. His uncle dies, also from A.L.S. Mr. Doctoroff creates a nonprofit called Target ALS, raises tens of millions of dollars for A.L.S. research.

It is 2017,

and Mr. Doctoroff looks down from his office on the 27th floor of a tower in Hudson Yards, a neighborhood he named. He sees the glass-capped entrance to the 7-train station, New York’s first subway line extension in decades.

He is now the chief executive of Sidewalk Labs, a start-up Mr. Doctoroff founded with Google after running Bloomberg L.P. for six years.

“Just as we hoped, Midtown leapt to the west and West Chelsea burst to the north, creating a new neighborhood in Manhattan’s last frontier,” Mr. Doctoroff writes in his autobiography.

His schedule slows a little. Mr. Doctoroff finds a therapist to figure out how to spend his extra time. He digs into his childhood in Birmingham, Mich. His father, Myles, drove a blue Chevrolet station wagon to work at a no-name law firm. His mother scolded her husband. Why can’t you be more ambitious?

He remembers his mother’s anger, her need for prestige. He watched his father rise to become chief judge of the Michigan Court of Appeals.

“I didn’t want to disappoint my mom,” Mr. Doctoroff says. “That has been the major motivating force in my career. And I didn’t even know it.”

Years later, he and Alisa vacation in Iceland. He walks up a hill and loses his breath — strange, he thinks. Back in New York, in October 2021, a doctor offers a diagnosis: The same disease that killed Mr. Doctoroff’s father and uncle; the same disease he had already raised millions to fight.

Mr. Doctoroff had always tried to predict the future, and sometimes it seemed like he could. But that was just his hopes underpinned by his confidence. Now he can see the future with a measure of certainty, and it is finite and hard: This is how he will die.

He calls Manish Raisinghani, the chief executive of Target ALS. He delivers the news, and an order.

“He said, ‘I want to grow this organization. Don’t think small. Think really big. And let’s move really quickly,’” Mr. Raisinghani recalls. “I’m stunned. But he’s not missing a beat.”

Mr. Doctoroff decides to fund partnerships between scientists, biotech companies and venture capitalists during the earliest stages of research. Hopefully this will encourage drug companies to weather the expensive and risky process of seeking approval from the Food and Drug Administration.

He figures he needs $250 million. A year and a half later, he has only $22 million to go.

“They’re going to have a ton of money,” Jeff Rothstein, a former Target ALS board member who directs the Brain Science Institute at Johns Hopkins University, says of its current trajectory.

Mr. Doctoroff’s body fades quickly. He wakes one morning to find his abdominal muscles have disappeared in the night. His whole life, people described him as athletic and good-looking. He enjoyed that. Now his belly falls over his belt like a basketball. He jokes that this is the worst part of A.L.S. He lands the joke by setting his eyebrows to show it is not entirely a joke.

The disease attacks his lungs. Breath comes raggedly, turning his powerful voice into a soft, pausing tremolo. Central Park stands across the street from his house. The nearest train station is three blocks away. Both too far, now that he loses breath on a short flight of stairs.

“There is some upside to having A.L.S.,” he says. “I don’t have to walk the dogs.”

Adapt. Optimize. Take a complex situation and make it better. The disease will have his body. It will not claim his optimism. Can’t ride the subway? Buy a Vespa. Can’t walk without losing breath? Buy hiking sticks, use them to squeeze air into the lungs. A black brace over his right calf prevents Mr. Doctoroff’s foot from dropping as he walks. Black pants prevent people from noticing.

“I’m right-handed, but now I eat with my left hand. I’m getting good at it!” he says. “I find, actually, adaptation is fun. There’s got to be a better way. I can do it. I can look at it as a positive thing instead of a negative.”

It is May 7, 2023,

and Mr. Doctoroff sees 600 scientists, investors and drug company executives in a hotel conference room in Boston for the annual meeting of Target ALS. They discuss the first drug ever to reverse symptoms of the disease.

“We’re in a new era for A.L.S. research,” Mr. Doctoroff says.

He no longer tries to see the future. He is here, present, and it’s simple. With A.L.S., there’s no time to worry about time. He flies to Puerto Rico, Knoxville, Detroit and Provence with family or friends from high school. He rides his Vespa to meet his rich friends. He delivers his Target ALS pitch, wins a handshake and a promise for $200,000 or a million. He’s still on the board at Bloomberg Philanthropies and the University of Chicago, still gets dragooned into helping the mayor and the governor plan New York’s future. For a normal person, this is a busy career in full bloom.

For Mr. Doctoroff, it is retirement. His dread is replaced by a calm that surprises him.

“You worked so hard when we were growing up,” Ariel Doctoroff says to her father. “We talked about how you were never around, basically. Except for on Saturdays.”

“That’s not true,” Mr. Doctoroff says.

“I know. It’s not true,” Ariel says. “And you tried extremely hard to be present.”

Now, at last, he is.

“I never enjoyed any achievement or anything we accomplished because I was always on to the next thing,” he says. “I’ve changed dramatically since my diagnosis. It’s funny. I just don’t think about the future much. And that has made me more patient. It has made me, I think, a nicer person.”

His voice grows weaker. His peace grows stronger. His will remains. It is 8:30 in the morning on a Tuesday in August. The man places both palms on the windowsill of his home gym. He groans, and allows his knees to drop to the floor. A tangle of ropes and rubber bands hangs from hooks on the nearest wall. A physical trainer, connected by Zoom, instructs Mr. Doctoroff to grab the thinnest, lightest band.

“I can do the heavy one,” Mr. Doctoroff says.

“You sure?” says the trainer.

“Yeah.”