On the night that Andy Lannigan spent 27 years trying to forget, he woke up in a bathtub up to his knees in his own blood after being stabbed in the chest and abdomen in an attack that stole the life of his best friend.

He and Andy Murphy, both 17 at the time, had been wounded by a 12-inch carving knife in retaliation for a gang fight two weeks previously. Stabbed twice in the heart, Mr Murphy didn’t survive the night.

It was his friend’s murder and the guilt that plagued him that sparked Mr Lannigan’s almost thirty year addiction to heroin, cocaine, street valium and alcohol.

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Andy, 45, said: “What kept me using was that he was a better person than me. I was quite violent and I didn’t have other people’s feelings at the forefront of what I was doing. He did. He was a really nice person.”

Now clean for 18 months, Andy is preparing to teach his first yoga class after using the ancient practice to help him recover. He credits his own yoga teacher Dr Lou Prendergast of The BodyMind Studio in Glasgow for helping to turn his life around.

Andy’s wiry 5foot 5 inch frame still bears the scars of the ambush while those in his mind have finally been laid to rest through his daily practice of yoga, meditation and pilates. He volunteers at Phoenix House, the rehab centre where he beat his addictions, three days a week and is looking forward to teaching his first Yoga of 12-Step Recovery (Y12SR) class.

Y12SR is a therapeutic style of yoga designed to address the effects of addiction and trauma, created by American yoga therapist and former sex worker and drug addict Nikki Myers, and taught exclusively at The BodyMind Studio.

HeraldScotland:

Andy joined the Den-Toi gang when he was just eight years old as a fighter, deployed with other children to taunt rivals into bigger clashes with the older gang members. He came from a normal working class family but fell into a bad crowd, leaving school at 14 and graduating to shoplifting, armed robbery and selling drugs.

He said: “I was good at school but left because of the violence. In Easterhouse back in the 80s there was a lot of gang fighting. We’d go down and fling bricks at each other. It was something I was good at. I’m not proud of that.”

During his time on the gang frontline he saw someone have a slab dropped on his head, "which wasn't nice", and another man getting run over by a motorbike.

He reels off what his addiction cost him - a promising welding career, homelessness, stretches in prison, his three children and a 20 year bout of Hepatitis C - now beaten.

But he doesn’t spend time regretting his past, having worked through his guilt and regret in therapy and on the mat.

He started practicing yoga during his six month stay at Phoenix House, leaving once a week to attend a hot yoga class.

He said: “I started coming for the heat and it got me out of rehab for a couple of hours and then I found out I liked it.”

Six weeks later he was off methadone but was still tormented by his racing mind. He said: “I was in peer groups just rabbiting a lot of garbage. I couldn’t concentrate on a single thought.”

And then on the mat, something clicked: “I never noticed anyone else in the class and that helped me to learn how to focus. I went to group the next day and spoke about one thing and it was the first time I’ve ever done that. My head slowed down really quickly because of the yoga.”

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Andy’s ease in helping others in recovery and that he still attended yoga regularly after leaving rehab, prompted Lou to encourage him to teach.

He said: “I trained because I know what I get out of it so it would be good if other people could get something too.”

Yoga has given Andy the tools to process negative memories and emotions, like the ones that surface when he thinks back to the night Mr Murphy died.

The two huddled in a close as rival gang members stabbed at them through a double-glazed door. Andy was stabbed in the chest and abdomen, his stomach was pierced and he lost five and a half pints of blood.

He remembers being dragged into a flat, wrapped in four curtains and hauled into a bath.

Scared of knives since, he retired from gang life almost immediately.

He said: “I still can’t remember much. I didn’t realise until I started looking at why I was taking drugs that I blamed my mate for leaving me, he was my best pal and anything I did he was at my back. Because I didn’t know what had happened in the close - did he run away? I know now he didn’t.

“What I didn’t want to do [was feel things] and then I got offered heroin and I took it and everything disappeared.”

When describing his new life, Andy says he’s “quiet, peaceful, happy” but he won’t ever forget where he came from.

He said: “I’ve got a lot of scars but I know how to deal with anything now. I’ve got confidence in myself and my own ability so I know what I can and can’t do. I know I can’t drink, I know I can’t take drugs and I know I can help people.

“I was in fight mode for 27 years. I was still fighting and grabbing hold of that knife because I’d been knocked out and when I woke up I still thought I was in that scenario and when I started to learn how to breathe, that’s when I started to feel better.”