Getty Images North America 1 / 3
Getty Images North America 1 / 3

Cancer has never met a tougher competitor than Diem Brown, her friends and reality-TV show co-stars said.

"She maintained such an optimistic, positive outlook in life," her co-star and longtime friend Johnny "Bananas" Devenanzio told Us Weekly. "She was like, 'I don't want to know what stage I am. I'm gonna f------ beat this thing. Just having that optimism when everything looks bleak, dude ... It was that mental strength that she had to never give up. She never did, until her last breath."

RELATED: Former MTV stars: Where are they now?

Diem passed away after a long bout with cancer on Nov. 14, 2014, but prior to her death, she participated in MTV's "The Challenge: Battle of the Exes II," which aired her final episode on Jan. 20.

RELATED: Inside Snooki's nuptials

The airing of the episode brought a lot of emotion back to her castmates at a press event held the same day.

RELATED: Stars flaunt their bikini bodies

Jordan Wiseley said, "She was a fighter. That's what these shows were for her, [a chance] to go out there and show everybody that it doesn't matter what's wrong -- she's gonna fight. She's gonna compete. And nobody's going to tell her not to."

Because of her sickness, Diem was forced to leave the MTV show, but some think she would have actually won.

"I first met her on Battle of the Exes I, and she and CT [Tamburello] took second place," Leroy Garrett told the magazine. "Had she not been sick ... I'm sure they probably would have won it if she were in a healthier state. It definitely sucked."