Prince William is getting open and honest about the death of his mother, Princess Diana. In the upcoming BBC One documentary, A Royal Team Talk: Tackling Mental Health [1], the Duke of Cambridge discusses losing his mom at a young age and how that affected him. In a preview clip, he describes the heartbreak and emotional toll it took on him.

"When you are bereaved at a very young age — any time, really, but particularly at a young age, I can resonate closely to that — you feel pain like no other pain," said the royal, who was 15 years old [2] when Diana died in a car accident [3] in 1997. "And you know that in your life, it's going to be very difficult to come across someone that's going to be in even worse pain than that. But it also brings you so close to all those other people out there who have been bereaved." William then went on to encourage people to speak more openly about their emotions and mental health [4].

William has previously opened up about Diana [5] and how he felt when she died. He's shared that he misses his mother every day [6] and has expressed admiration for Diana's impact on bringing awareness to causes such as AIDS research [7]. As a patron of Child Bereavement UK [8], William has also honored his mother at charity events hosted by the organization that aims to help families [9] affected by the death of a young family member. In 2015, he spoke about Diana attending the 1994 launch of Child Bereavement UK, saying, "What my mother recognized back then and what I understand now is that grief is the most painful experience that any child or parent can endure."

Watch William talk more about coping with grief and loss when A Royal Team Talk: Tackling Mental Health premieres Sunday, May 19, on BBC One.