"I've tried committing suicide. But I didn't, look at me now."
Mathieu has since removed the words because "I didn't think it would go viral," he said.
But the sentiment behind the words hasn't changed.
"I think the biggest thing is to be open about it," he said Tuesday after the first day of Cardinals minicamp at the team's practice complex. "Part of it is reaching out to others trying to help; part of it is self-counseling, talking about it, not shying away from it. Most people try to isolate themselves and pretend like things are all good when a lot of times, that's not how it is."
I'm sitting in that jail cell thinking, 'I don't know if I want to go back out there and face the music.' I didn't know how I was going to commit suicide in the cell, but that was the direction my life was heading.
The breaking point for Mathieu came as he sat in a jail after police searched his apartment and found marijuana during what would have been his third college season. Mathieu had already been kicked off LSU's football team for failing multiple drugs tests, and he felt his life and dreams crumbling beneath him.
"I'm sitting in that jail cell thinking, 'I don't know if I want to go back out there and face the music,' " he said. "I didn't know how I was going to commit suicide in the cell, but that was the direction my life was heading."
Unexpectedly encouraging words stopped him.
"Believe it or not, my cellmates were encouraging me, telling me I was a good football player; telling me I don't need to be thinking about this," Mathieu said. "That's probably why I really didn't do it, but there was an actual moment where I was thinking about, and I'll never forget that feeling."
Out of that low point came a resolve to turn his life around and rededicate himself to football.
"I wanted to be an example for others again," he said.
"Some people are going to be supportive and encouraging; others are going to say you're doing it to get attention," Mathieu said. "That's just part of saying anything."
But Mathieu has genuine hopes and he is still mulling how to use his experience to help others.
"I want to start a foundation called Second Chance," he said. "I was given a second chance, so I want to reach out to different groups of people. It would be nice to give that opportunity to others."
Mathieu said he has already talked to his agent and marketing people about forming the foundation. Although he still isn't practicing with the team as he rehabs from a torn LCL and ACL, he hopes to start the ball rolling on his foundation when the Cardinals finish minicamp on Thursday and his days aren't completely dominated by football.
"People go through a lot of things. They can be every-day personal things, not just suicide," he said. "I just want to reach out and use this platform for something positive and be an inspiration to people who want to see me as an inspiration."
Mathieu still has no idea whether he'll be ready for the start of the 2014 season, despite the recent chatter that he could be. But given where he's been in his life, he considers rehab a minor bump in the road.
"It's a long process, and it's going to continue to be a long process," he said. "I just try to come to work every day and stay on top of my rehab -- just continue to push myself. I don't try to get too down about it; I don't try to get too excited when my knee is feeling good. I just take it as it comes."