But that was before the Belfast man took his very first job under the golden arches, aged just 16.
Three decades, various roles and several geographical locations later and the 46-year-old is now Business Manager at McDonald’s restaurant on Belfast’s Boucher Road.
“I started as a Crew Member at McDonald’s in the Abbey Centre,” he said.
“A new restaurant was opening when I applied for a part time job coming up to Christmas… the company offered flexible working and it was a great team.
I continued to work for McDonald’s during my A Levels and my history degree at the University of Ulster’s Coleraine campus…and 30 years later I’m still here.”
Stewart, who now lives in Whiteabbey, was promoted to Crew Trainer, then Area Leader while he continued his studies.
He told how he was subsequently planning to do a postgraduate certificate in education (PGCE) but then opted for two further promotions (Shift Manager, then Second Assistant Manager) instead.
His fate was sealed, however, when he was asked to help open a new McDonald’s restaurant in Newtownards.
“After three years I was promoted to First Assistant and then I became Business Manager in the Downpatrick restaurant; I’ve never looked back,” he said.
Stints at restaurants in Lurgan, Belfast’s Victoria Square and Donegall Place in Belfast city centre followed before Stewart arrived at his current location in 2020.
“I moved during Covid and it’s where I’ve been ever since,” he said, adding that BBC TV and radio presenter Stephen Nolan “is a regular” at the Boucher Road eatery.
Stewart puts his longevity down to “the people and the working environment”.
“There’s an excellent team spirit and I’ve made friends for life along the way,”: he said. “I’m still friendly with people I worked with in the Abbey Centre.”
Stewart said he thrives in the fast-paced environment, relishes the daily challenges of the job and enjoys helping his employees move up through the ranks.
In fact, he said he sees himself as being a teacher for older students.
“I’m working with staff, many of whom are aged between 16 and 21, dealing with individual issues,” he said.
“It’s like being a teacher in a business environment. There’s a training culture and I’m constantly trying to develop my employees’ skills.
“McDonald’s offers staff NVQ opportunities and there is continual development and career progression.”
On top of his day job, the father-of-one has completed two marathons to raise money for Ronald McDonald House Charities Ireland.
“I started running during the pandemic. I did the Belfast marathon in 2023 and then Dublin last year,’ he said.
He also cycled across Cuba for charity 13 years ago, alongside Franchisee Paul Connan.
“We covered 650 miles in seven days, which was amazing,” he said.
“I hadn’t been on a bicycle since I was a kid but I bought a bike for £100 and trained for six months ahead of the trip.
Mr Connan, who owns and runs McDonald’s at Boucher, said Stewart was an inspiration to all.
“Customers and staff enjoy working with Stewart and we feel very lucky to have him as part of the team,” he said.
“He has a great work ethos and an excellent team spirit and he’s a great example to others.”
Although he describes himself as being “not naturally sporty”, Stewart has also participated in hikes up the Mourne Mountain and he’s cycled around Lough Neagh in aid of charity, and he’s been actively involved in community football events spearheaded by McDonald’s.
Additionally, he represents the interests of Northern Ireland on the Business Managers Council, an internal McDonald’s organisation, which is something he’s “very proud to do”.
Despite having 30 years under his belt already, Stewart’s ambition remains undiminished.
He said: “I like to progress and move forward so I’d really love to be a franchisee one day.”