The 31-year-old, head of hockey at Edinburgh Academy, represented the national team in his playing days but was unable to fulfil his potential as a major knee problem forced him to retire aged just 23.
The positive aspect of that was that he was able to make a head-start in his coaching career. Duncan capped his rise over the past seven years by being placed in charge of Scotland's women last December after a spell as interim head coach.
"I felt like I had more years left in me as a player but my body said no," he said, reflecting on his earlier-than-planned venture into coaching. "It's turned out to be a blessing in disguise because I was then thrust into the coaching domain a lot younger than most people.
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"I found myself working with people who were much older than me but I had great opportunities getting experience coaching the under-16 boys and under-18 and under-21 before I joined the senior programme as an assistant.
"It's all happened pretty quickly but getting hurt and committing to it early has almost been a positive rather than a negative. It drives me on to succeed as a coach because there's something within me that frustrates me a bit that I never got the opportunity to excel and see what heights I could get to as a player.
"That early ending has definitely spurred me on to be successful here. I had no break between playing and going into coaching, and fast-forward seven years and here's where I am.
"I have to pinch myself regularly. A year ago I was the assistant coach and we'd just been to the European Championships so to now be the head coach at the Commonwealth Games is a bit surreal if I'm honest.
"My wife asked me recently what's the thing that will make you realise you're there and I said I think it will be that moment when we sing the national anthem before the South Africa game (this Friday). That will be pretty special."
Scotland – ranked 17th in the world – are the seventh-ranked team at the Games in Birmingham. They are in Pool B alongside New Zealand, South Africa, Australia and Kenya, and Duncan is hoping they can punch above their weight.
"In some years gone by we've gone to Commonwealth Games just to make up the numbers but we've had a lot of conversations about wanting to change that narrative," he said.
"We're ranked seventh but we're never happy with just achieving our ranking. We want to go higher and do something special. Team Scotland's top finish was in Melbourne 2002 when they came fifth and we'd love to try and replicate that.
"The main thing is to go out there and be comfortable and confident with the way we play and see where it goes. I'm excited to see what we can do. We're itching to get going."