AUSTIN, Texas -- Campaigning for a presidential candidate can be a grueling task, with hours spent block-walking, making phone calls and knocking on doors, but for one Elizabeth Warren campaign worker, a simple knock led to a life-saving situation. 

From any observer, it looked like a FaceTime chat between two friends as UT Austin student Parisa Mahmud caught up with Iowa resident Carly Routh. While states away, and 10 years apart in age, the pair have a special bond. 

"I just told her how much of an inspiration you are to me," said Mahmud to Routh.  

About two weeks ago, Mahmud was volunteering as a door-knocker for Warren's campaign in Iowa. It was business as usual, until she knocked on Routh's door.

"I noticed that her breathing kind of erratic and her eyes were kind of red. It just seemed like something wasn't OK, so I asked if she was OK," said Mahmud.  

Routh said no, and asked Mahmud to come inside. 

"She sat down, started crying and told me she was a veteran, she has PTSD, and she was in the middle of committing suicide," said Mahmud.  

Mahmud saved her life. 

"If she would not have shown up and knocked on my door, I was at that point where I had made up my mind that I was going to take my own life," Routh said. 

Routh says she's taking steps to regain her health, and is grateful for a quick-thinking door-knocker on an especially dark winter day in Iowa. 

"I'm really glad that I had the instinct to ask if she was OK and like ask all those questions, and I really hope anyone in that situation would do the exact same thing I did," said Mahmud.  

It was a routine campaign outreach that couldn't have come at a more critical time. 

Mahmud shared the story on Twitter and received a surprise phone call from Warren thanking her for advocating for mental health.