Isaksen epitomises the impact that the right or wrong coach and culture clashes can have on your career.
After moving to Lazio, Isaksen had a hard time adjusting to the direct style of Maurizio Sarri and Igor Tudor, which is somewhat a result of the way coaches are educated in Denmark.
Modern management principles and a pedagogical approach can sometimes stand in stark contrast to the often hands-on approach you can expect south of the Danish border.
Isaksen experienced this first-hand at Lazio, where in just over a year he had to get used to the management style of no fewer than three coaches.
The first two of whom, Maurizio Sarri and Igor Tudor, did not develop the coach-player relationship that the young forward needed to maximise his full potential in the harsh football reality of the Italian capital.
However, it's not as if the attacking player from central Jutland hadn't already been exposed to such discipline at a young age, when he began to make a name for himself at the age of 12 through promising performances at FC Midtjylland's "Guldminen".
"The first time I got to know Gustav was at the Crown Plaza Cup. I was over there to watch our under-13 team and I heard about a young lad who, when he scored, shushed the opposition. He celebrated his goals like crazy," says the club's Sports Director Svend Graversen, who was the coach of the under-17 team at the time, to the club's website.
Despite the success on the pitch, Graversen had to speak some home truths to Isaksen, who displayed a cheeky attitude during his time at the after-school programme.
"He's the player I've sat with the most times and tried to make him understand that 'Gustav, this isn't working. You can see that for yourself.' It was just a long time to get him to realise it. He was just a young man who hadn't quite got his head round things," says Svend Graversen.
The Dane is currently experiencing his best time in Rome, where the Lazio fans love Isaksen after his fabulous left-footed strike gave Lazio a fine 1-0 victory at the Diego Armando Stadium in Naples.
That was the Isaksen that Lazio president Claudio Lotito fell in love with when the Eagles were humiliated 5-1 by Midtjylland in September 2022 - a match where Isaksen excelled as the star player.
So keen were the Italians on Isaksen that, according to FCM's sporting director Graversen, it only took two phone calls to negotiate a price of DKK 110 million in the 2023 summer transfer window.
"It was clear that this was a player Lazio wanted. At the same time, they had set a framework that they had priced him at, and that framework roughly matched the framework we had set. It's very rare that it happens like this, because it will normally be a negotiation process over a longer period of time when the deadline is so far away," says Graversen to FCM's website.
On his way to the Eternal City, Isaksen had a Lazio scarf hung around his neck at the airport and was interviewed for the club's video platform despite not having passed the medical.
At the same time, he was celebrated as a folk hero by a massive crowd who had certainly not forgotten the treatment he gave their team just eight months earlier.
Those scenes of jubilation, however, were in stark contrast to Isaksen's first season at the club, where loneliness, language difficulties and problems adapting to the Italian style of play quickly became part of his reality.
From the outset, the challenges piled up for Isaksen, who struggled to carve out a place in the starting line-up with direct competitors like Felipe Anderson, Mattia Zaccagni and the ageing Barcelona legend Pedro, while the coach had little faith in him.
To tell the truth, the young forward was nowhere near the kind of level that made him the top scorer in the Danish Superliga with 18 goals the previous season.
"I need a coach to talk to me and tell me what to do. The first two coaches I had didn't really communicate. I had a hard time getting a picture of what they wanted from me and how I should play," said the Dane.
"They play much faster, more physical and with a much greater focus on tactics than I've been used to," Isaksen explained in an interview with TV2.
The forward also comes from a very close family and being so far away from them has hurt him mentally.
"Of course, it's not as easy to live in Italy as it would be to live in Aarhus (in Denmark), where you have your friends and family close by. But luckily I have a cleaning lady and you can get food every day, so it's not that bad," the Dane tells BT.
Language difficulties have also made life a challenge for Isaksen in Italy, who was told from the start that he had to learn Italian if he wanted to communicate with Maurizio Sarri.
"When I arrived on the first day, I greeted him and he said to me: 'I'm actually really good at speaking English, but I don't want to do it. So you'd better learn Italian quickly,'" Isaksen revealed.
"I've had to learn it the hard way, it means a lot, not only in the football world, but also when you're at home and have to go downtown and order a coffee. You always meet someone on the street who wants to talk, so knowing the language just makes it a little more fun to be there," said Isaksen to Tipsbladet.
Even when Lazio sacked Sarri and hired Igor Tudor, the problematic situation did not change for Isaksen. He might have gradually found some form but he had a tricky relationship with the Croatian, which he also aired to the Danish media as his chances of gaining a place in the European Championship squad grew smaller.
"We didn't get each other 100% and I wasn't the player he wanted. He wanted different types, but I think I did well under him, so it was frustrating," explained the Dane.
"I didn't play the last five or six games leading up to the European Championship. It was a bit of a tough time," admitted the forward, who was urged by many to leave the Rome club during the summer transfer window.
"Tudor started rumours that I was going out on loan. But if I had changed clubs, I might have run into the same problems somewhere else and had to start all over again. I told my agents that even if something exciting came along, there was a 99% chance I would stay," said Isaksen, who in Marco Baroni, soon found a coach with perfect chemistry.
Baroni has put the doubters to shame with an attacking style that suits Isaksen far better and has given Lazio an excellent start to the season where they are just three points behind leaders Atalanta in fifth place. Baroni is universally praised not only for his tactical ideas, but also for his treatment of the team, including Isaksen.
"He wants the forwards to constantly challenge their opponents and get them on slippery ice. We talk every day and he gives me clear ideas about what I should do and how he wants to use me. It works fantastically.".
The sky is certainly the limit for Isaksen in the wake of Baroni's arrival in the Eternal City.