His 20-year-old daughter Hannah, a student at the University of St Andrews, was wearing it for her first marathon, and Austin says when he saw her coming into view it gave him the idea to get back in training.
"Waiting for her, seeing thousands of athletes in various moods of exultation and exhaustion after 26 miles made me wistful to have one more go," he says.
"When Hannah came in, that did it for me. Not just because I was so proud of her achievement but, in addition, she was wearing her Batman T-shirt, which is the same as I have always worn to run races."
Austin started running in the 1980s and did three Glasgow Marathons, as well as half marathons and 10Ks until about four years ago.
Now 54, he aims to get in shape for the Belfast Marathon in May and will be writing a regular diary along the way, which he will share with readers of the Evening Times.
I AM overweight and I have a sedentary job that is quite stressful," he explains.
"I would not want to portray myself as being this brilliant older athlete because I'm far from that.
"I want to encourage other people to just make the most of themselves. It can be done. I have one project, I have the lead up to it and I know how I can manage that and how good it will be for me."
He has already started training - running six miles, swimming about 1800 metres and walking five miles - three times a week, which will increase leading up to the marathon.
"I used to smoke when I first started running in the 1980s and as I began to do the training I would run and then have a cigarette at the end of it," he says.
"As the training progressed, more and more I didn't want one at the end and there came a day when I'd run 14 miles and I just took the cigarette out of the packet and thought, no, I'm finished."
All the years of running have taken their toll of Austin's knees and ankles and he says he is aware of taking things gradually.
"I'm realistic enough to know that OK, I've always trained, but I have creaks so I'm just doing it gradually."
He also wants to lose about 42 pounds by the event and has started a healthy eating regime, with help from his wife Yvonne.
She cooks from fresh ingredients every day, which means a balanced diet coupled with Austin's fitness regime is already making a difference.
"The one thing that has niggled me for years is that although I'm fit and have a relatively moderate life-style, I don't go out partying and I don't go out to pubs, I've had great difficulty shifting the weight.
"I need this routine of exercise so that I can tie in the dietary changes."
As well as running, Austin has trained in karate. After a break, he took it up again last year and gained his 3rd dan black belt. He admits the re-establishment of regular exercise gave him the confidence to train for the Belfast Marathon.
He got his 1st dan black belt in 1984 and says the full body workout of karate particularly appeals to him.
He says: "It's also good for the mind because it is a complex series of exercises and sequences. If you are fighting with somebody it's a battle of wits."
Our Active 2014 campaign, with partners Glasgow Life and NHS Greater Glasgow and Clyde, is targeted at improving health in the year of the Commonwealth Games and building a lasting legacy of physical wellbeing.
FOCUSING on events and individuals of all ages, we aim to improve the health of as many people as possible in the community.
We will target a series of health goals, including basic fitness, obesity, diet and smoking cessation and deliver the message that small changes in activity and lifestyle can make a huge improvement in health.