NEW YORK — Backstage at the Nokia Theatre, about 30 minutes before he took the stage at "A Night for Vets: An MTV Concert for the BRAVE," 50 Cent was in the middle of lacing up his combat boots, when all of a sudden he stopped, adjusted his cap, leaned back in his chair and recalled what it was like to perform for U.S. troops in Iraq in 2004.

"It was intense, man. There was an intensity there," he said, eyes moving toward the ceiling. "A lot of [soldiers] write these death notes before they go on missions, they write these notes that they want their loved ones to read. ... They're in this environment where death is everywhere."

Clearly, the event made a lasting impression on him — so strong that he's carried the memories of the soldiers he met that day with him ever since.

"A lot of the people I met [in Mosul] had been there since my first record came out — they'd been there since '03 — and you could tell, man. There was an intensity there," he said. "It was eye-opening. It was like, 'You think you've had a tough time? ... These people have a tough time.' They're in this environment that's more intense than anything you could imagine."

Which is why, when he was approached earlier this month to appear at the BRAVE concert — which, in addition as serving as a "thank you" to the men and women serving in our armed forces, also aimed to raise awareness of the MTV's BRAVE petition for veterans' rights — 50 said yes without thinking twice. Not only because he's met the troops himself, but because he's become quite aware of the difficulties those troops have faced when returning home.

"I don't think there's any way you can understand it unless you've been there and seen it," he said. "When they come back and realize that everyone went on with their lives, you know? People went to work, did their thing, and the troops come home and it's tough for them to realize it, man. They have it tough, and that's part of the reason I did 'Home of the Brave' [the 2006 film in which 50 played an vet returning home from Iraq], to try and tell that story to people."

And with that, 50 is called to the stage. But as he meets fellow G-Unit members Lloyd Banks and Tony Yayo in the hallway, MTV News manages to get in one more question: He's played before all sorts of crowds, all over the world — what's it like to perform for an audience of vets?

"They've got an energy. You gotta come hard, you know? These guys are tougher than the tough guys from my neighborhood, 'cause they went over there willingly," he laughed. "I know I wouldn't want to put myself in that position. There are some tough guys in the crowd out there tonight."

Don't miss "A Night for Vets: An MTV Concert for the BRAVE," presented by MTV's Choose or Lose campaign and CNN to support veterans of the Iraq and Afghanistan wars. The show features performances by 50 Cent, Ludacris, Kanye West, Linkin Park, Hinder, Saving Abel and more, and airs Friday at 8 p.m. ET on MTV.