One of the people who made it clear to him that he wanted to be one of the world's top coaches was the one who was never really himself. He is a modest coach and a very humble man.
His background has a lot to do with that. There is a very down-to-earth mentality and strong accent in the east of the Netherlands where he comes from. They look up to the places where the big offices, industry and the country's parliament are, because they are a bit less flash there.
Ten Hag has a strong accent, but his situation is different. He comes from a very rich family, so he doesn't need to go for the big jobs at any point in his career. They own financial firms and a real estate company.
His father wanted him to go into that company but when he was young he realized he didn't want to work in that field.
He doesn't need the big jobs because of his family wealth. He knows he doesn't need football to survive so he can follow his own principles.
His football philosophy has been the same as that of both the Barcelona and the Amsterdam teams. He likes to create things on the pitch.
I followed him when he was an assistant at PSV Eindhoven, just as he was an assistant at FC Twente. He was an important part of those clubs. He was so strong that the managers were reliant on him. It was a pleasure for them to have him.
He loved his job as the reserve-team boss. It was almost like a dream for him to have a manager who would work the same way he wanted to work. He said that he loved talking to him and spending time with him. The set-up worked for him because he had to produce players for the first team as the reserve manager.
He comes across as a bit obsessive and that makes it hard for players. It takes a lot of work and a lot of attacking players to get a style like Dutch Total Football. It leaves a lot of space and you want your defenders to play high up. It requires a lot of risk and you have to be a maniac to make sure that your players know that they can't make mistakes.
All of his players say they have learned a lot from him.
Ten Hag will spend a lot of time on the training pitch. At Manchester United, he will pay attention to the 19th or 20th most important player, not just the star players. He takes on players with different characters and he doesn't mind how much time he spends with them, he will give all his time to them.
He gets the respect from the players because they see the effort he puts in to improve them individually. If he thinks the talent is there, he will make sure they fit in.
He is willing to take on the job at Manchester United. He would like to be in a tracksuit for many hours a day. He doesn't consider himself an office man, he would have gone to his dad's company if he did. I think one of the main points about his potential appointment is that he would rather not be on the phone with agents. He will want a sporting director or assistant with the ability to do that.
I don't think it's a good idea for him to think that part of his job is fitting into the traditional English way of management.
He doesn't want to think he has to take on the whole of Manchester United. He will want to give the club an identity again, and he will do that by wearing a tracksuit.
Ten Hag has never felt comfortable in front of the camera. He might find it difficult to get his message across. If he went to a German club with serious interest, he would be in his comfort zone because he lives on the German border. German is a second language for everyone in that area.
A manager who takes charge of one of the biggest clubs in the world based in the UK, with all the publicity and media around him, should be able to command the English language really well. It will not stop him from being successful, but it will help if he improves. He has been practicing his English a lot.
The players found it hard to get used to his long training sessions and long talks on the pitch because his newspaper was critical of him at the beginning.
He built a good team, but he was given good players. He had immediate success but it was the way that he and his team played against Real Madrid and Juventus that caught the attention of the people.
When Matthijs de Ligt and Frenkie de Jong were sold to Barcelona, it was easy for new players to fit in because they had given the club and the team such an identity.
One reflection from the man himself might be illuminating if United fans want to know about his approach.
Epi Drost was his coach at FC Twente, the same club as Ten Hag.
Epi had a soft spot for me because I was the youngest in the squad. He was a huge fan of football. The most important aspect of the game was creativity. I learned a lot from him.
I would like to compare him to Ronald Koeman. They both played as leaders at the back who oversaw the game and the team from that position. Both managers are huge fans of Total Football, but neither wants to be as adventurous as the other. There is one big difference between the Manchester City boss and Ten Hag, and that is that the Dutch has a slightly more realistic approach. They have more interest in the defence than he does.
If he goes to Manchester United, the people he works with will quickly learn that he is a very loyal person.
He started out in the FC Twente academy at the age of 14 and was quickly moved up to the U18s where he played for many years with the same guys.
But while he was there two of his best friends died, one in a plane crash in Suriname. Andy Scharmin, a boy who was destined to play for the Netherlands, was selected for an exhibition game by Suriname, who didn't have a formal national team, and he chose to go. The plane he was on crashed and killed a large number of the team. He was one of Ten Hag's closest friends - they did everything together. That was a massive upset in his life.
A third friend took his own life. All three were destined for international careers. He drew inspiration from wanting to succeed where his friends never got the chance to.
A lot came from the loss of friends. Even now, that still drives him on.