Yemeni-born Mo Nasir was inspired to box by "Prince" Naseem Hamed
A rising star in boxing is using the "discipline" of the ring to help turn round the lives of teenagers.
Commonwealth Games bronze medallist Mo Nasir, 22, from Newport, says he hopes he can be a role model for youngsters.
Ex-Monmouth Comprehensive School pupil Ieuan Evans, 17, said meeting Nasir and taking up boxing had "saved his life".
Nasir told BBC Radio Wales documentary Boxing is Fighting Back he was encouraging teenagers to use the sport to reject a life of drugs or violence.
The Yemeni-born light-flyweight is deciding how best to turn professional after his medal win at the 2006 Melbourne games, said: "You see a lot of people on the streets, they're drinking, taking drugs, causing problems, problems with the police and I think when you bring them to the gym it changes them completely because it's a discipline."
He told the programme: "Some kids are violent and I think boxing does change them because I have been teaching a lot of 'naughty' boys and they are changing completely.
"I've been training a few boys in the gym now and their family have been ringing me, thanking me how they changed."
Ieuan, from Monmouth, said he had been out of control, smoking cannabis by age 12 and drinking at 13.
He said: "I was quite drunk all the time and stoned and constantly smoking fags. I must admit I've done some stupid things, walked up the town with blow and people thought it was a cigar. I was a mess by the time I reached the top of the town."
But things changed shortly after his mother mentioned Ieuan's passion for boxing to the school's deputy head Andy Williams.
He took the teenager to St Josephs Boxing Gym in Pill, Newport, and arranged for him and a group of other pupils to train with Nasir.
He said: "Quitting weed was the hardest thing. The fags were hard. I was angry a lot so I'd go there and take all my anger out and everyone used to say to me 'ever since you've gone to boxing you think you're big and hard' and it wasn't that.
"It was stress - you try and quit fags and it's not the easiest. Most people think it's easy but it's not.
"I stayed in my room all the time. I went to the gym all the time I used to do the fitness [training] and then go home.
"If I go out, it would only be for about 10 seconds. As soon as I'd see a joint going up I'd be 'right, I'm off, see ya' because, the temptation, I can't handle".
Mr Williams said: "Lots of people take drugs because they don't value themselves, they don't see that they're worth anything, so drugs take them to a different place.
"But for Ieuan there was that slight glimmer of hope that his self respect and self esteem could be developed if he just concentrated and focused on that sport.
Monmouth Comprehensive has set up a boxing club and twice a week Nasir trains pupils with a whole range of backgrounds.
Boxing is Fighting Back is on BBC Radio Wales on Saturday 31 May at 1330 BST and 1830 BST.