He's making a bid to complete a vertical marathon: 26.2 miles up the 21 storeys of the stairwell at Glasgow's Hilton Hotel. If successful will be a unique record breaker, as it has never been done before.
Stephen hopes to complete the challenge in less than 70 hours by running and walking in three-hour shifts with brief 45-minute breaks to eat, drink and have a quick power nap, starting on April 3.
More than 90 pupils from the school will be there to give him their support over the three days, some even joining in and running ascents.
"When I spoke to my old friend Willie Wight, who is head teacher at the school, about my project he was really keen to get involved," says Stephen.
"The school has an internal committee made up entirely of senior pupils and this year they've chosen the hospice as their charity - as had I, so it was perfect.
"One of the things we want to do is highlight to everyone we can that the hospice needs help and while you're doing that you can also climb a few stairs and get yourself fitter and healthier.
"We want youngsters to understand as early as they can that it's easy to do the things that keep you in decent shape on a daily basis.
"Sport has been a huge part of my life but I know that isn't the case for everyone.
"One of the messages we're trying to deliver is how simple it is to help the heart and lungs and keep you in better shape by doing really simple things like walking up the stairs."
Stephen will be burning his way up the stairs 671 times, covering a total of 238,205 stairs.
The 47-year-old says he is feeling positive after his experiences taking part in ultra marathons around the world, including running 280 kilometres through the rainforest in the Brazilian Amazon.
Anyone wishing to accompany Stephen in one or more of his 671 ascents can register at www.humanachievementzone.com.
A minimum donation of £25 is required to secure a place, with all money going to charity.
All proceeds will go to the Hilton Community Foundation which will donate to the Prince & Princess of Wales Hospice Brick by Brick Appeal to build a new purpose-build facility near Bellahouston Park.
The hospice provides free care for people with terminal illnesses, primarily cancer, and support for their families and carers.
With approximately 1200 patients every year, space at their present home on Carlton Place is limited and they plan to relocate to a purpose-built facility on a site adjacent to Bellahouston Park, gifted by Glasgow City Council.
This will allow the hospice to lower their age limit to those aged 15 and above.
To find out more about the Brick by Brick appeal, back by the Evening Times, to build a new home for The Prince & Princess of Wales Hospice, visit www.ppwh.org.uk or call 0141 429 5599.
You can donate to Stephen's vertical marathon via Just Giving at www.justgiving.com/myverticalmarathon.
By involving pupils from Hillhead High School in his challenge, Stephen embodies the ethos of our Active 2014 campaign, which aims to improve the health of Scots in the year of the Commonwealth Games and build a lasting legacy of physical wellbeing.
n Active Austin's fitness mission: Page 37