Bono had to hold the note - even though it wasn't him singing. When the U2 frontman agreed to write a song for director Jim Sheridan's film In America, the key was crafting lyrics and a melody that would extend the melancholy wistfulness of the final scene.
But why does the singer for the biggest band on the planet, a man who has been nominated for a multitude of Grammys and a Nobel Peace Prize, busy himself with movie songs?
"Film is part of my education," Bono said. "Growing up in Dublin, our experiences of art and culture came from music and movies. So that's always been a part of me."
In America is based on Sheridan's childhood memories about the death of his brother, mingled with his adult experiences emigrating with his wife and two daughters from Ireland to New York City in the 1980s.
Bono watched a rough cut of the movie in 2001 and began crafting the song Time Enough For Tears, drawing off elements of the film's score by Maurice Seezer and Gavin Friday.
"It's definitely about death and all those Irish melancholy songs. We're great at singing songs about death," Bono joked about the tune.
With U2 and sometimes on his own, Bono has worked on a lot of theme songs for a lot of movies, including Gangs of New York, City of Angels and the James Bond thriller Goldeneye.
Sometimes they are what Bono described as "adjuncts", unrelated pop tunes tagged onto a movie as a promotional device. Hold Me, Thrill Me, Kiss Me, Kill Me from 1995's Batman Forever was one of those, along with Elevation, which turned up in 2001's Lara Croft: Tomb Raider.
The singer seems to have more affection for songs written specifically for a particular film story, like The Hands that Built America from Martin Scorsese's Gangs of New York, a mournful rock ballad that travelled from the film's Civil War-era riots in the 1860s to September 11, 2001.
In America was a chance for Bono to collaborate again with Sheridan, a longtime friend who once owned a theatre in Ireland where Bono performed rock songs as a teenager.
"He's been a mentor to me," Bono said. "It's like he's always been a presence in my life."
They previously worked together on Sheridan's 1993 film In the Name of the Father. Bono, Friday and Seezer co-wrote the theme You Made Me the Thief of Your Heart for singer Sinead O'Connor.
"There are songs you have to put together slowly. And then there are songs that are gifts. Thief of Your Heart was one like that," Bono said.
In America offered a different challenge. The film is narrated by a little girl, who tries to help her father overcome the death of his son. In a closing scene, she brings her father to tears by pretending to see the boy waving goodbye to them from the moon.
Although he didn't want to retell the story in song, Bono said "there are certain marks to hit" in the lyrics".
"The moon was a symbol of faith at the end so I wrote 'The moon is milk and the sky where it's spilled is magic'," he said.
Andrea Corr, who sings with her siblings in the Irish pop group The Corrs, performs the lullaby over the closing credits. Corr was picked to perform Time Enough for Tears because Bono wanted a voice that paralleled the young actress in the movie.
"We didn't want Andrea to sing like a pop singer," he said. "We wanted her to sing in that almost childlike voice." - Sapa-AP