“Pain is temporary, film is forever” is a movie adage that has been printed on many images. It take a great deal of effort to make a movie, but that pain is temporary and the film is forever.
 
The line is from the film Three O’Clock High (1987), written by Richard Christian Matheson and Thomas Szollosi. The film’s central character, Jerry Mitchell, is due for a beating by a bully after school hours (three o’clock). A fellow student and aspiring filmmaker wants to film the event, telling Jerry, “Pain is temporary. Film is forever.”
 
American actor Michael J. Fox used the line in 1989 to describe making the Back to the Future films. American actor Leonardo DiCaprio used the line about his role in the films Titanic (1997) and the earlier This Boy’s Life (1993), and said that he’d learned it from that film’s director, Michael Caton-Jones. New Zealand film director Peter Jackson inserted the line into his film King Kong (2005). American screenwriter and director John Milius has also been credited with the line, but it’s uncertain when he said it.
     
   
Wikipedia: Three O’Clock High   
Three O’Clock High is a 1987 high-school comedy film directed by Phil Joanou, written by Richard Christian Matheson and Thomas Szollosi, and starring Casey Siemaszko, Anne Ryan, Richard Tyson, Jeffrey Tambor, Philip Baker Hall and John P. Ryan.
 
IMDb (The Internet Movie Database)   
Three O’Clock High (1987)
Quotes
Bruce Chalmer: Pain is temporary, film is forever.
     
10 October 1987, The Morning Call (Allentown, PA), “‘Three O’Clock High’ is an interesting failure” by Richard Freedman (Newhouse News Service), pg. A65, col. 1:
Other classmates are worse. Two ardent junior cineastes want to make a documentary of the day’s events (“Pain is temporary,” they assure Jerry. “Film is forever.”), and the Accounting Club is busy working out the odds on Jerry’s survival.
     
18 October 1987, Washington (DC) Post, “Rockin and Reelin’ With U2;Phil Joanou, Documenting the Days of the Irish Supergroup” by Joseph P. Kahn, pg. F1:
At one point in the plot line, Jerry Mitchell, the film’s protagonist, is confronting the full horror of a day gone impossibly wrong: embezzled funds, concealed weapons and an impending fight to the death in parking lot with a bully of Frankenstein proportions. Two classmates corner Mitchell and attempt to cut a deal. Since both of them are applying to UCLA film school, they argue, why not let them follow Mitchell around with a camera and document his near-certain demise.
 
“Pain is temporary, Jerry,” one of them says, voicing an ethic heard often in Hollywood, “but film is forever.”
 
21 November 1989, Ottawa (ON) Citizen, “Back to the Future II: Hollywood gamble: sequel split in two” by Jamie Portman, pg. C5:
Pain is temporary,” Michael J. Fox says with a grin. “Film is forever.”
 
Which is another way of saying that going back to Back to the Future has been worth every gruelling moment of the experience.
     
26 March 1993, USA Today (McLean, VA), “Talking all about love with Walters” by Jeannie Williams, pg. 2D:
SNEAKS: Bill Murray got to beat up on Robert De Niro in Mad Dog and Glory, and in This Boy’s Life, it’s the turn of an 18-year-old newcomer, Leonardo DiCaprio.
 
Unfortunately, young Toby, DiCaprio’s character, also gets more than his share of beatings from De Niro as a twisted, emotionally and physically abusive stepfather in this movie from a true story, opening April 9. It’s no movie for kids, believe us.
 
DiCaprio said at a recent private screening that those intense scenes left him “feeling riled up and angry . . . I think it did look realistic so it paid off. Pain is temporary, film is forever!”
   
29 March 1997, The Independent (UK), “Romeo gets that sinking feeling” by Ryan Gilbey, pg. 5:
(Leonardo DiCaprio, speaking about acting in the film Titanic.—ed.)
“I’d have to say I probably won’t do anything like it again. It was closer to manual labour than shooting a film. Whenever I’m working, I always think of something Michael Caton-Jones {who directed a 16-year- old DiCaprio alongside Robert De Niro in This Boy's Life} told me: `Pain is temporary. Film is forever.’ And now it’s over, well, all respect to people who do those sorts of movies, but it’s not for me.”
     
21 January 2006,

(London, UK), “Leaders: King content,” pg. 11:
“PAIN is temporary, film is forever.” That hopeful thought, which found its way into the original script of Peter Jackson’s recent re-make of “King Kong”, might be seized upon by today’s beleaguered entertainment industry.
 
Twitter
Elizabeth
@spitesprite
would like to remind everyone that, as Peter Jackson says, “Pain is temporary - film is forever!”
3:47 PM - 25 Sep 2008
   
Twitter
Toni A
@Toni_hime
Watching 3 O’Clock high. “Come on guys, this is my life we’re talking bout.” “Pain is temporary, film is forever” LOL. N
7:38 PM - 18 May 2009
   
Twitter
Alexa Joy #Revoke50
@MadameArkadina
“There’s a quote that will be instilled in me always - ‘Pain is temporary; film is forever’” - Leonardo DiCaprio.
5:23 PM - 28 May 2009
   
Twitter
Tony
@Oracle77
Replying to @NoelClarke
@NoelClarke Heh! But like Robert Zemeckis says “pain is temporary, film is forever’... Your suffering was worth it. Cool video in the end.
7:57 PM - 28 May 2009
   
Twitter
Debra Joy
@SchuggaJoy
RT@ACTORSandCREW “Pain is temporary, film is forever.” - Michael J. Fox
2:09 PM - 16 Jul 2009
 
Twitter
Stage 32
@Stage32
Pain is temporary, film is forever!
- John Milius
11:41 AM - 5 Oct 2011
     
6 September 2014, The Independent (Dublin, Ireland), “It takes a village to make a film” by Garret Daly and Martina McGlynn, pg. 14:
What were we thinking? A husband and wife team with very little budget behind them set off to make their first feature film. We must have been mad, however “Pain is temporary, film is forever” according to the great John Milius.
   
Google Books
Horror Films by Subgenre:
A Viewer’s Guide
By Chris Vander Kaay and Kathleen Fernandez-Vander Kaay
Jefferson, NC: McFarland & Company, Inc.
2016
Pg. 86:
“Pain is temporary, film is forever.” This famous saying appeared on-screen in the 1987 film Three O’Clock High and has also been attributed to celebrities as varied as Michael J. Fox, Peter Jackson, and John Milius. Interestingly, the quote is often associated with filmmakers who are trying to convince actors to do things for a movie that could be extremely dangerous. Funnily enough, it works.
 
Collider
The 29 Most Rewatchable Movies Ever Made
BY COLLIDER STAFF     AUGUST 20, 2018
“Pain is temporary, film is forever.” That quote has been used ad nauseam to drive home the fact that cinema is engrained in permanent ink, and that however difficult or arduous the process of making a particular film, the end result is (hopefully) worth it. The truth is not every movie is worth standing the test of time, and some age more gracefully than others. But film is forever, and that’s one of the great things about the artform
   
Syfy Wire
THE SWAMP THING COSTUME AND MAKEUP ARE HOT, STICKY, AND TOOLS FOR SELF-LOVE
Caitlin Busch @caitlinmbusch
Jun 11, 2019
(...)
“It’s that old adage of film,” he (actor Derek Mears—ed.) muses. “That pain is temporary and film is forever. That’s what you try to hold on to when creating a character like this.”