Prince Harry has described his son Archie as giving him a new focus and goal as he wore a jacket declaring "I am daddy" on a visit to the Netherlands.
Harry spoke to former soldier Dennis van der Stroom, 31, as he took a break from paternity leave to visit The Hague for the one year countdown to the Invictus Games being held there.
Mr van der Stroom, who served in the army from 2006 to 2011, said: "Harry talked about how having a small child was his new focus and new goal and I told him how a couple of months ago, I was struggling with my mental health but my wife's pregnancy has given me a goal.
"Above all he said he was just amazed by the miracles in the world, and how his child has made a lot of people happy.
"He also told me he's really happy that his son is so far very quiet."
Mr van der Stroom, who hopes to compete in the Netherlands Invictus team in track and field and sitting volleyball, said they also talked about losing a mother.
He said: "He said missing a mother is like missing some kind of security, how you need that as a son and it falls away when you lose your mother."
Harry wore a jacket embroidered with the words Invictus Family Daddy, with I Am Daddy highlighted in yellow, and tried out archery and cycling at the event on Thursday, a day after he and the Duchess of Sussex showed off Archie Mountbatten-Windsor to the world at a Windsor Castle photocall.
Former Royal Marine and Invictus Games medallist JJ Chalmers said Harry had described fatherhood as "amazing" but "hard work" when they spoke at the launch event.
"He said that (Archie) slept for the first 24 hours like all babies do . . . and then he woke up," he said.
Mr Chalmers, who has been friends with Harry since the first Games in 2014, said: "I see the guy with a buzzing smile on his face still.
"Like any father he lights up even more when he speaks about his son and how proud he is of his wife and what she's doing right now in his absence."
He said it was "remarkable" the duke had attended the launch just days after the birth.
He said: "In some ways it shows you just how much it means to him, to drag himself away, because I know what it's like being a young father - you don't want to leave and if he had the choice he would be at home."
Asked if Archie would accompany him to the games in 2020, Harry replied: "I've no idea."
After a short speech in which he praised the determination and courage of the competitors, the duke was presented with a special Invictus Games babygro for his son by Princess Margriet of the Netherlands.
He drew laughs from the crowd by holding it against himself to model it.
As well as the babygro, Harry was presented with gifts including a new soft rattle toy, some newborn socks with I Love Daddy written on them and a stuffed toy bird.
Daimy Gommers, seven, whose father Paul, 46, competes in archery, gave the duke a giftwrapped blue and white cube baby to for his son.
Her mother Danielle, from Apeldoorn in the Netherlands, said: "He was nice but he was a bit ashamed because the present was for his son not for him but he had unwrapped it!
"He looks well and he's got lots of energy to be here and he's always so spontaneous"
She added: "I think he's a terrific father."
Wellwishers gathered to greet the new father as he arrived at the Sportscampus in Zuiderpark, some with more gifts, including a teddy and a piggy bank in the shape of a corgi, for the new royal addition.
Harry said he was "delighted" to be in the Netherlands for the occasion and praised competitors of the games, which he launched in 2014 for injured, wounded and sick servicemen and women.
"It is your resilience, your determination and your courage which draw crowds in their thousands," he said.
"Leaving them feeling more inspired, moved and proud than they ever thought possible. You have already proved - anything is possible."
He called on the country to make the games its own and said: "We chose you for a reason, and it wasn't just because I like the colour orange!"
Harry joined in with an archery session in the sports hall, managing to hit close to the centre of the target, and got on a bicycle for a tour of the park.
The duke also watched a wheelchair basketball training session and viewed some Jaguar Land Rover prototypes with mobility technology.
He posed for pictures with Invictus Games competitors before leaving at about 2.30pm to head home to his wife and son.