In a packed room at a college in Walthamstow, in north-east London, a former student is speaking to a class. Amani Simpson has shown the pupils a short film he made based on his life, and now there’s a Q&A session. The questions include what did he study here and how did he get the money to make a film. His answers: music and events management, and through crowdfunding. Then a girl at the back asks what he thinks is the solution to the current knife crime epidemic. That’s a trickier one.

Simpson was stabbed seven times in an attack in 2011, in the chest, arms and legs. He lived to tell the story and to make the film, Amani, with his friend Joivan Wade, an actor. It starts with him in an ambulance, covered in blood, questioning his faith and reflecting on a life that seems about to end too early. The film was released in January, and has more than 1.6m views on YouTube.

Simpson is from a devoutly Christian family in Enfield, north London. He played the violin, went to grammar school but did not fit in, did not have any positive role models, rebelled and got angry. He says: “You end up trying to make all these other guys like you, trying to fit into this group of boys who essentially don’t like you, you’re changing your values to suit them, when really they don’t know what it is they’re trying to achieve.”

He got expelled from that school and another, and then spent three months in a secure unit for children. “You go to the unit on the basis that everyone has given up on you,” he says. “I don’t think getting expelled from school is something that helps kids. It kind of ignites the anger even more, and also you’re putting them in environments that you’d want them to be completely separate from.”

Without any kind of direction in his life, Simpson became a “roadman”, dealing heroin and crack to addicts. But then he made the decision to turn his life around, reconnected with his family, did the course at the college we are now in, and began to work in music events, as well as starting a property letting business. He was not involved in criminal activity when he was stabbed. “And that’s part of the message I’m trying to get across,” he says. “It’s not like I was part of a gang or anything.”

It was an argument outside a nightclub he was flyering, which then escalated. He said the wrong thing to a group of boys he didn’t know and they attacked him. He didn’t even realise he had been stabbed at first. “I was wearing a Puffa jacket, it felt like getting punched, I couldn’t feel the blades going in my body or anything like that. It was only after when the bouncer lifted up my jacket. It was a moment when you feel like you’re not going to see your family again.”

Amani Simpson talking to students at his old college. Photograph: Alecsandra Raluca Drăgoi

He says he is glad he was stabbed, as it led him to what he now does. In the ambulance, he promised to himself and to God that he would help other young people at risk of getting caught up in violence and crime. That is why he is here today, talking to these young people, showing them his film, trying to be that role model he did not have. “I believe in positive role models, the need for more BAME leaders. In the school I went to I wasn’t represented or understood. You need someone who is relatable to. That’s why I like going into schools and colleges, empowering kids on the ground, because I can tell them I’ve been in your shoes, I know what it feels like to be you.”

Which the average politician does not. Simpson thinks most politicians act in their own best interests, they do not listen to young people but criminalise them. “It’s like basically saying: we know what the issue is, it’s due to poverty, we can look at the stats, but although we know that, we are still going to put the army on the street and do more stop and search. To me that doesn’t help anybody, except to kind of fuel this agenda of trying to limit the futures of the young people who are coming up.”

He has a message for parents, too. “It’s about learning a bit more about your kids, and not judging them, just because times have changed, ‘that’s not what we’re used to do’, that can’t be the basis of the conversation.” Simpson, 28, says he would like to be a parent some day. “I think children are amazing.”

What about, even more importantly, his message for the children and young peoplewho are carrying knives, or thinking about it? He says: “The best thing I would say is you’ve got to make key decisions about the future you want to have. It’s easier said than done. It’s easy to say put the knife down, it will stop knife crime, stop the killing, stabbings and stuff, whereas in actual every day it’s very difficult to say stop it, because you can stop it but the other side isn’t going to. So I would just encourage anyone who’s young not to get involved because it’s a lot harder to leave once you jump into that kind of environment.”

And what about the question of what should be done? Simpson welcomes a public health approach to knife crime. “Because you get multi-agency conversations happening, it becomes a community issue rather than just ‘let’s treat this as a crime’. That allows certain people to be helped when it comes to things like poverty, opportunities, this holistic approach about how you support young people.”

Plus, he says, in order to shift this culture of youth violence and low aspiration, we need to be telling “more positive stories, not just the stabbings but ones of some of the kids doing amazing things or have turned their lives around.” Stories like his.