The 38-year-old disappeared from his Preston home last month and sparked a missing persons appeal before he was found safe and well in Liverpool.
The ex-chairman of the Professional Footballers' Association has campaigned to raise awareness of mental health issues and launched the Clarke Carlisle Foundation for Dual Diagnosis - a condition that has been described as "mental health problems co-occurring with drug or alcohol abuse".
The former Burnley defender described his recent turmoil to presenter Adrian Chiles on his BBC 5 live Daily show.
He said he had been "strolling around" Liverpool and was "headstrong set on the most convenient way to kill myself" when a passing stranger intervened.
Carlisle said: "I didn't know what was going on. I didn't have my phone with me; obviously I was lurking in the shadows, looking for, you know, this place and that place, trying to mind my own business.
"This car pulled up while I was sat in a park and a guy came over and said 'Oh, I thought it was you. You know your family is looking for you?' and I guessed as much but I didn't know the extent of how far it had gone.
"This guy, you know, sadly for him, his friend had killed himself a few days earlier and he said 'I thought this was you and I could not go by not checking' because he'd heard the state that I was in and he just wanted to help.
"And, you know, I didn't want his help, I didn't want his help sat in the park, but this guy came and sat next to me and he hugged me and he cried on my shoulder, just urging me to get in touch with my family."
The man called Carlisle's pregnant wife, Carrie, and put Carlisle on the phone.
Mrs Carlisle told Chiles: "I heard his voice and it was like, literally like, the best moment of my life because I thought I'd never hear from him again, and this wonderful gentleman stayed with him."
She added: "It's horrifying to realise that you've been engaging not with your husband but with an illness that manipulates the individual to the point where they feel they're a burden.
"We're surrounded by love all the time but what I didn't know is that he couldn't feel that love. It was like he was living in a glass box.
"I judged a crisis by my own standards. What I thought was minor was literally the end of the world for Clarke and if I could go back I would stop using my own mental framework as a reference."
Father-of-three Carlisle spent three weeks in hospital and is now recovering at home.
In December 2014 he tried to take his own life when he jumped into the path of a 12-ton lorry on the A64 near York.
Tim Kendall, NHS England's national clinical director for mental health, said: "Stories like Clarke's are extremely important in helping people to feel that they can seek help.
"Improving mental health services by increasing investment, offering people treatment closer to home and integrating mental and physical care, remains one of the NHS's top priorities.
"Whilst there is still some way to go, we now have the biggest national programme for community talking therapies for common conditions like depression and anxiety, which is increasingly available to people to tackle these problems before they escalate."