Special Forces: World's Toughest Test Loses 5th Celebrity—and It's Not Who You'd Expect

The unexpected hurdle sent the 32-year-old into a mental tailspin.

"There's gonna be a voice in my head numerous times throughout this that's probably going to be telling me to quit and bail out," the retired sports star admitted in a confessional. "Take the easy way out. Fighting that and resisting that urge is the main focus."

Feeling defeated, Manziel announced to Billingham, "I'm out," before Billingham encouraged him to fight through the moment of weakness by replying, "What do you want to do? Think about it. Last chance."

Ultimately, Manziel had had enough and declared, "I'm out," before taking off his recruit armband.

Manziel's quitting meant all three members of his team failed the challenge. And the Heisman winner admitted that he simply reached a personal barrier that he couldn’t overcome.

"My biggest struggles within myself are just giving up at times," Manziel reflected in a confessional. "Losing that battle mentally. And that's been something I think has been a weakness for me for sure. You have to live with the decisions and the actions you made and there is no going back and changing things now."

As for his teammates' reactions to his exit, Gia commented, "I can't believe Johnny just tapped out. I was gonna for a second. I had a panic attack."

Meanwhile, Chanel struggled to catch her breath and admitted, "I swallowed so much dirt."

See how the rest of the cast fares in the brutal competition when Special Forces: World's Toughest Test airs Thursdays at 9 p.m. on Fox. And keep reading to see the 13 celebs still competing this season.