Prince William has spoken candidly about the death of his mother, Diana, Princess of Wales, describing his bereavement as a “pain like no other pain.”

Speaking in a BBC documentary on mental health, William also says that his time working as an air ambulance pilot gave him the impression that death was just “around the door,” and the thoughts had become a problem until he spoke with someone.

“That raw emotion… I could feel it brewing up inside me and I could feel it was going to take its toll and be a real problem. I had to speak about it,” he said.

The comments were part of a discussion about personal struggles with soccer stars Peter Crouch, Thierry Henry, Danny Rose, Jermaine Jenas and England’s manager Gareth Southgate. Each shared their own difficult experiences.

Prince William and his brother, Prince Harry, have championed the cause of addressing mental health issues, hoping their frank admissions on their own struggles will encourage others in need to seek help.