Homeless World Cup: Wales teams target joy on and off the pitch
Wayne Ellaway spent 20 years in a destructive cycle of prison sentences, substance misuse and sofa surfing.
He said he lost many friends to drugs over the years and does not understand how he survived.
During that time, he also used to wander around Cardiff's Bute Park in a "desperate mess".
But from Saturday he will be back in the same park as head coach of Wales' men's/mixed and women's teams taking part in football's Homeless World Cup.
The 17th edition of the tournament, which is being held in Cardiff, runs from 27 July to 3 August and features about 500 players from 48 countries.
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Mr Ellaway, from Cardiff, had stopped taking drugs by the time he played for Wales at the 2015 tournament in Amsterdam.
Now he hopes those in the team he is coaching can use the experience to help rebuild their own lives.
"I think they can see where I've come from," said Mr Ellaway, who now has a home and job as an outreach worker.
"I used to walk around Bute Park lonely, desolate, desperate, nowhere to go, homeless, and now I'll be coaching Wales at the Homeless World Cup on the park I used to walk around in a desperate mess."
He added: "I'm so grateful for another opportunity. In 2015 I thought it was over [after the tournament] but it's just continued to get better and better and better.
"To be socially excluded for so long, to be homeless, to be addicted to drugs, to be vulnerable and to be in all of these positions - and then you see them now, young confident men, young confident women who are now socially included and no longer socially excluded.
"That's what it's all about for me - the human part. The football is fantastic but it's the human beings behind the football."
Jennifer Gattrell will be one of those players in the women's team over the next week.
"On the day, when I'm lining up singing the national anthem, I think that's when it starts kicking in," the 34-year-old goalkeeper said.
"For years I hated playing in goals. It's only the last two years I've embraced it and if people say I'm good, then I'm good enough for this."
Ms Gattrell was homeless for about a year and a quarter after her grandmother was taken into a nursing home.
During that period, she also lost her job, friends and family but now has the keys to her own home.
"I just want to make my nan proud. I just wish she was here to see the day," she said.
Osian Lloyd is getting the chance to play at the second attempt after missing out in Oslo two years ago because his passport did not arrive in time.
"It's a whole better tournament playing in your home country in front of your home crowd - I'm raring to go," he said.
The 19-year-old from Blaenau Ffestiniog, Gwynedd, has previously spent time on the streets and sofa surfing, but said football had helped turn his life around.
"It gives me a purpose," he said. "Family situations have changed dramatically as well. I went to see them the other day for the first time in like a year and a half.
"It's not just football, it changes your whole life."
He added: "I've been offered a place in Swansea to live and to be more involved with football and different opportunities with jobs, my career and myself.
"It's given me that platform to believe I can do what I want."
Bonny Jewell, 27, from Cardiff, has also got plans once the tournament is over.
"I've always wanted to represent my country in sports and having my father there as well as my two children there. They are proud of what I've achieved.
"Next, I'm setting up a project for the homeless doing shared accommodations and hostels as well as a community centre, a charity shop and a cafe.
"I really want to help them change their lives because it's not nice. You don't know their background but all they ask for is a conversation. It makes their day. You can't do too much."
Their involvement comes through Street Football Wales (SFW).
SFW founder Keri Harris was working for The Big Issue Cymru when, in 2003, he was tasked with putting a team together for the first Homeless World Cup in Austria.
It was life-changing for Keri as he realised Wales needed a programme which offered social inclusion through sport.
SFW is behind Cardiff hosting this year's Homeless World Cup.
"To be able to go out and play in front of a home crowd, hear your national anthem in front of hundreds of people, that's going to be an emotional thing, and hopefully inspirational as well," he said.
"They can lift themselves and do the nation proud."