In a clip released by BBC for an upcoming special A Royal Team Talk: Tackling Mental Health, the 36-year-old royal opens up to professional athletes about his own struggle with loss as a child and how it forever changed him. Princess Diana died in a car crash in 1997. She was 36.
"I think when you are bereaved at a very young age, anytime really, but particularly at a young age - I can resonate closely to that - you feel a pain like no other pain," he tells soccer stars Gareth Southgate, Peter Crouch, Thierry Henry, Danny Rose and Jermaine Jenas.
He adds: "And you know that in your life it's going to be very difficult to come across something that is going to be an even worse pain than that."
William goes on to state that, although getting struck by massive loss at a young age takes a toll, he immediately bonded with others who've also lost a loved one.
"But it also brings you so close to all those other people out there who have been bereaved," he says. "So instantly, when you talk to someone else… You can almost see it in their eyes sometimes."
As William strives to do with his charity Heads Together, he also discussed the importance of doing away with the British reserve with which his country is known for. Stating individuals need to "be able to talk about our emotions, because we're not robots."
"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," Dennis van der Stroom, an Invictus Games competitor said, via multiple outlets.
The 34-year-old royal also "talked about how having a small child was his new focus and new goal," according to van der Stroom, who added that Harry "said he was just amazed by the miracles in the world, and how his child has made a lot of people happy."