Donnie Wahlberg "cut off [his] life" for his role in 'The Sixth Sense'.
The New Kids on the Block star portrayed former mental patient Vincent Gray in the 1999 classic horror movie and he admitted he put himself through "hell" to prepare for the film, going weeks without washing and "starving" himself.
He said: "At that time, I did exactly what I needed to do for the role. I had to look like I was going through hell. I went to a really dark place.
"Nothing about me was right for the part, except for my total enthusiasm for the script.
"I starved myself. I would fast for two days then only eat steamed cabbage and drink beet juice. I would chew gum all day and I would literally walk around the streets to burn thousands of calories. I didn't shower for weeks.
"I just wasn't taking care of myself and I was a loner. That was as close as I could come to this guy. I definitely had to suffer in the only way I could.
"I was so hungry. I was depressed. I cut off my life to get ready for the role."
The 49-year-old star admitted the role was a "game-changer" and even now people are still surprised he was in M. Night Shyamalan's film.
He told USA Today newspaper: "This was a game-changer for me.
"Every day for years people would say, 'Dude, I didn't know that was you.' "
And Donnie will always be proud of the movie.
He added: "The movie is such a great source of pride for me. Not just my work but to be part of that group. Everyone brought it so hard for that movie."
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