On a Christmas night out exactly a year ago Brian Stirling was punched in the side of the head as he stood outside a pub in West Lothian. He was knocked to the ground, smashing his head off the pavement and died soon after.
His younger brother Alan says Brian was a "peacemaker" who had never acted violently in his life.
He was the victim of someone lashing out after too much drink and was in the wrong place at the wrong time, Alan says.
The 54-year-old bakery worker had been out for a few drinks in Bathgate on the Friday before Christmas.
In the early hours of Saturday morning he left the pub with his friend and was standing outside, a few doors down from the entrance.
His brother Alan says: "There had been a disturbance at the front door of the pub with some guy who had been thrown out.
"While this was going on, a woman approached Brian and his friend and asked if he could hold her bag so she could find her cigarettes.
"Brian, who was the sort of guy to help anybody, held her bag open.
"Unfortunately, on seeing this, the guy who got thrown out of the pub, ran over and punched Brian in the side of the head for no reason."
Brian fell over and smashed his head against the pavement.
He was taken to St John's hospital in Livingston with serious head trauma but they could not save him.
Alan received a call at 06:00 on Saturday morning but Brian was dead by the time they arrived.
"Nobody should go out for a few drinks and not get home the next day," he says.
It is seeking to highlight the severe damage a single punch can do.
They said a single violent act could kill or seriously injure the victim and it could result in a prison sentence for the attacker.
Alan Stirling says: "When you are in a bad moment, when you are ready to lash out at somebody, you have think very carefully about all the good things in your life and in the other person's life, all the stuff you care about, all the stuff you have worked hard for, in that one moment of violent stupidity, you are going to throw it all away.
"Not just for you but for the person you are going to lash out at.
"Do you really want to throw your life away on one punch?", Alan says.
Alan says the attacker only served 10 months before being deported to Poland.
"That's not justice for my brother's life," he says.
Craig Porter's life was also devastated by a single punch.
A brain injury suffered as a result of a punch eight years ago has left him unable to walk and with great difficulty speaking.
Craig, who is now 35, worked in IT for the Scottish National Blood Transfusion Service at Gartnavel Hospital before he was punched in Glasgow city centre in 2009.
He says: "I took for granted my life before this injury and I was warned 'your life is a bit too eccentric'.
"But I thought 'I'm just a lad, I'll be fine, it'll never happen to me'.
"But then I was in the wrong place at the wrong time. I got into a fight and I knocked my head on the kerb."
Craig says he was heading to get a taxi home after a night out when he and his friends "got into an altercation".
He says there was a stand-off.
"Then basically he punched me and that was it. Lights out," Craig says.
"I banged my head, instantly knocked out and cracked my head on the pavement."
Craig was in a coma for five weeks and doctors told his family that if he survived he would probably never breathe on his own.
They also said he would not talk or walk.
"It's been a hard slog," Craig says.
"I've not got there, far from it, but I'm getting there."
Eight years on, balance issues mean that Craig still can't walk or drive.
He can't write, his speech is affected and his eyesight is poor.
"Every few months I'll get down and think I'm not getting anywhere but then something will improve, my balance, my swimming or something," he says.
"I couldn't stand up before but now I can stand up and get dressed.
"I get incredibly sad at times but then I realise at least I'm alive and I've got a great support network."
No-one has been convicted of the attack on Craig.
He says: "I am proof of what one punch can do.
"Fortunately I am living proof which I can thankfully say. There are plenty of people who have not been as fortunate as me.
"I have got the chance to get as well as I can and I'm going to take it. Simple as."