There was a moment, just before Jim McGuinness began his first day as a sports science student at IT Tralee in 1997, when he thought about turning on his heel and heading home.

Far from his home in Glenties - 420km to be precise - and heading to college as a 25-year-old having previously quit school at 15, McGuinness had been removed completely from his comfort zone.

"I just questioned myself and doubted myself," admitted McGuinness. "A good friend of mine now, he was walking past and he said, 'are you sports science?' I said, 'yeah'. He said, 'I think we're in this room'. I just followed him in and two days later I had really settled."

Two years later, McGuinness graduated with a diploma in Sports Science, completed his degree at the University of Ulster Jordanstown and earned himself a Masters Degree in sports psychology at John Moores University in Liverpool.

In an interview that will air on Sky Sports tomorrow ahead of the All-Ireland final, the Donegal manager is described as 'the eternal student'.

It's true to a degree because while he is still learning, he's also imparting a great deal of knowledge to others around him, making his living these days as Celtic's performance coach and, for fun, inspiring his county to the sort of Gaelic football success they couldn't have imagined four years ago when they struggled terribly.

To think how it might have all turned out if he'd ignored that classmate and walked out of IT Tralee. He didn't, of course, and his 'Sliding Doors' moment passed. Aside from advancing his education while in Kerry, he also played in a star-studded college side that won the Sigerson Cup in 1998, the All-Ireland inter varsity championship.

Now, 16 years on, the 41-year-old joked that he's been texting old pals in Kerry for nuggets of information ahead of tomorrow's All-Ireland final. Unsurprisingly, his phone has been silent.

"The Kerry people were fantastic, really good people and really good to me," said McGuinness. "So on a personal level, it is a lovely final for myself. And I know it is a lovely final for the boys as well because this is Kerry they're playing and all that brings.

"At the same time, Kerry are looking for their 37th All-Ireland. We are looking for our third. So is it really the team you want to play?"

There is no sense of any inferiority complex in the Donegal dressing-room though. Demolishing holders Dublin in the semi-final having been installed as 10/1 outsiders with some bookmakers saw to that.

McGuinness possesses a unique ability to extract more from players than they might think possible themselves - the reason he was first hired by Celtic and retained even after Neil Lennon's exit.

As Donegal manager for four years now, the only dip in a generally upward-curving graph came in 2013 when they failed badly to defend the All-Ireland success of 2012.

"Injuries hit us hard last year," explained McGuinness. "We had players like Neil Gallagher who missed 68% of all training sessions. Karl Lacey missed 69%, David Walsh was 60, Anthony Thompson missed a lot, Mark McHugh the same.

"We just had too many players in the middle lines that missed so much. The average attendance this year is 93%. We have had everyone at the sessions and that has allowed us to create and move forward."

Now they stand on the cusp of greatness. A second All-Ireland win in three seasons would put them among an elite group of teams. You won't get 10/1 odds on it happening either. For many, they are actually favourites. If they do it, McGuinness may just call time and devote his energies fully to Celtic. Some believe he could even manage Celtic one day. Stranger things have happened in the life of Jim McGuinness.