Simon Whitehouse thought about taking a train to visit Philadelphia the next time he's in New York.
But when he learned the cities were about 100 miles apart, he decided to run the distance.
The ultra-run will take place later this month, when Whitehouse plans to start in New York the morning of April 27. By early afternoon the next day, the 37-year-old plans to be finishing his trek with a Rocky-inspired climb up the Philadelphia Museum of Art steps.
"It's going to be painful," he said.
Whitehouse, who is from Stoke-on-Trent, England, but now lives in Milan, is doing the run to raise awareness about mental health.
His brother, with whom he watched the "Rocky" movies as child, has suffered from schizophrenia for the past 20 years. Whitehouse has been treated for depression. He is using the run to raise funds for Mind, a U.K.-based mental-health charity.
"If I'm going to commit to train and do 100 miles, what a great cause to do it for," said Whitehouse, a global commercial director for Diesel. He'll finish the run on his brother's 40th birthday.
To get ready, he's read books and talked with others who have run ultra-marathons. He's planning to take walk breaks, but will go non-stop, without sleep. He's been lining up a road crew to travel with him by car, and speaking with locals about the best route take.
Whitehouse played soccer when he was younger and began running in January 2011, after a year of physical therapy following knee surgery. He had pain in a calf muscle this winter that limited training, but has amped up his runs in recent weeks.
One Saturday in February, he said he ran around the city of Milan twice, a distance of nearly 25 miles. His longest training run so far has been 60 kilometers -- about 37 miles.
A big challenge, Whitehouse said, will be running through the night.
"My main fear is the night," he said. "I don't know how the body feels when you want to sleep."
He ran a half-marathon last week, leaving his home at about midnight and finishing at about 2:45 a.m. Tonight, he's planning to do a marathon-length run overnight.
"I need to conquer this fear of running through the night," he said.
Whitehouse said he's never desired to run a conventional marathon or ultra-race.
"I get stressed out when there's a group of people," Whitehouse said. But, he said, his solo run means he won't feel adrenaline from the crowd.
He expects to leave New York around 10 a.m., and arrive at the art museum between noon and 3 p.m. the next day.
As he's prepared for the run, he's re-watched the "Rocky" films for inspiration.
"When you watch 'Rocky' as a kid, you think it's some cheesy movie," he said. But watching them again, he said, you "learn the lesson that he goes through."