The 33-year-old made her debut for Everton at just 16 years old during the 2007/08 season. She quickly made a name for herself, winning the PFA Women's Young Player of the Year award and lifting the Women's FA Cup in the following year.
Moves to Manchester City, Barcelona and Atletico Madrid followed, which gave her the platform to solidify her spot in the England squad with 79 caps across her career.
"Strange really", Duggan said when asked by how it felt to call an end to her career.
"For any professional in whatever sport, the timing will always come. The fact it is today feels a bit weird and it will for the next few weeks.
Trending"A lot of thinking over the summer but happy I can finally walk away from the game with it in a much better place than when I started. I feel content with that."
Her career has taken her far and wide across Europe but ultimately it came full circle in the end, as the Liverpool-born forward returned to Everton three years ago in a move that would prove to be her final one in the professional game.
"You never plan for retirement," Duggan added when asked if she always envisaged finishing in blue.
"It's kind of just a feeling and you can't predict what will happen next. I just felt now is the right time to walk away and be happy with what I've done, on and off the pitch.
"It's kind of nice that my career has gone full circle. I started at Everton, and I finish here, it's a nice moment."
Duggan featured in 22 Women's Super League games for Everton in her first season back, scoring two goals and adding one assist, but missed the entirety of the next campaign after announcing she was pregnant with her daughter, Luella.
Her next move after retirement is yet to be determined but what is certain is her family will be at the forefront of any decision made.
She said: "I had offers from around the world but none that felt right, when you have a baby, they become your priority. It didn't feel right but I think I've made the right decision."
When asked about what avenue she did want to pursue in her post-playing days, Duggan admitted she is eager to continue working in football but wants to discover where her talents best lie before committing to one role.
"I'm not too sure what is next," she continued. "It's a bit too soon but I'll be the type to dip my toes into different things.
"I want to stay in the game, I've always had a passion for football, and I've always helped younger girls and guided them where possible.
"I've loved working with brands and sponsors to raise the profile of the game, so hopefully I can continue do that. Maybe some agency work, helping the next generation and punditry is something I've always enjoyed.
"I just want to find out what I enjoy and I'm good at. But obviously spending some quality time with Luella."
While many will focus on her accolades and honours on the pitch, Duggan's impact off it must also be applauded.
Her eagerness to open the discussion about pregnancy in the women's game and the clear demonstration that players can return to the highest level after starting a family is a glowing example set to future generations - but she is not done there.
"I think the women's game is at a great level but there's more progress to be made. Going through the pregnancy and going on that journey, there's areas to improve. If I can help, that would be great. Just seeing the game go from strength to strength, I'm so proud of the journey.
"The sky is the limit for not just women's football but women's sport in general It's fantastic to see the strides and even nicer to be a part of."
Four domestic teams, just under 300 appearances and over 90 goals - but most importantly, the game she is leaving is better than the one she arrived into thanks to her time in the sport.
Everton
Manchester City
Barcelona
Atletico Madrid
England