Prince William, Princess Kate and Prince Harry share candid conversation on 'life-changing' moment of parenthood, grieving for Princess Diana

— -- Prince William, Princess Kate and Prince Harry have released a candid new video for their Heads Together mental health campaign discussing some of the most personal issues they have faced, including parenting and coping with Princess Diana's death.

Kate, 35, and William, 34, the parents of Princess Charlotte and Prince George, opened up about the profound effects of becoming parents and the challenges they faced in the first few weeks after George was born in 2013.

"Having a child, particularly your first child, is a life-changing moment, nothing can really prepare you for that," Kate said. "Remember the first few days with little George. You have no idea what you're doing. No matter how many books you read, nothing can prepare you for it."

William agreed saying, "There's no rule book. There's no training that teaches you how to do it. You just learn from previous generations and hope that you can translate into what you want to do."

William and Kate spoke movingly about how overwhelmed they were despite the support they received from family in the immediate aftermath of George's birth.

"Do you remember up in Anglesey, we'd had our couple weeks of family support and then you were keen to get back to work, and I was, 'Yeah, I'll come with you of course,' so we scooted off back to Anglesey with George. Those first few weeks were a steep learning curve," Kate recalled.

"A steep learning curve massively," William concurred. "When you have children it puts your own emotions and own life into perspective massively."

William, Kate and Harry, 32, also spoke poignantly, and for the first time on camera as a group, about the 1997 death of William and Harry's mother, Princess Diana, and how her death shaped their lives.

"Considering everything that you boys sadly went though and the trauma you experienced ... I do think it's incredible how strong and how you've been able to cope really," Kate said to her husband and brother-in-law. "And I put that down to your really early years and your childhood experience, but also the relations you've got."

Kate added, "You're amazingly close," to which William replied, "Most of the time," as he and Harry laughed.

Kate told William and Harry that despite the tragedy, the support they've given each other was a blessing in dealing with their own grief.

"Some families aren't as lucky as you guys have been and being able to share things," she said.

"We have been brought closer because of the circumstances as well, that's the thing," William agreed. "You are, you know, uniquely blinded because of what we've been through but even Harry and I over the years have not talked enough about our mother."

Harry agreed with his brother, saying, "No never enough."

Harry, who was 12 when Diana died, revealed earlier this week that he sought counseling two decades after his mother's death. Harry said he sought help at the advice of William after largely trying to ignore Diana's death because it was too painful.

"I always thought to myself, what's the point of bringing up the past? What's the point if bringing up something that's only going to make you sad," Harry said to William and Kate in the new video. "It ain't going to change it. It ain't going to bring her back. And when you start thinking like that it can be really damaging. And you always said to me, 'You've got to sit down and think about those memories.'"

He continued, "But for me I was like I don't want to think about it."

The conversation between William, Kate and Harry also covers topics including the emotional changes new parents go through, the stresses of modern childhood and dealing with trauma in the workplace. The video was shot at Kensington Palace on the afternoon of April 19.

The royal trio are looking ahead to this weekend's 2017 Virgin Money London Marathon, in which a team of more than 700 runners are running on behalf of Heads Together.

William and Kate acknowledged in the video it was Kate's idea to make mental health a priority of their charity work.

Kensington Palace said in a statement William, Kate and Harry made a decision to "shine a spotlight on the power of conversations, both to shatter stigma on mental health and to help people get the help they need."

"The Duke and Duchess of Cambridge and Prince Harry have been overwhelmed by the response to the Heads Together campaign. We are in the middle of a truly national conversation on mental health," a Kensington Palace spokesman said. "They are incredibly grateful to everyone who has shared their stories in recent weeks. And having asked others to start conversations on mental health with their friends and families, they wanted to show that they are taking part as well."

Speaking of the new video, the spokesman said, "They hope the film shows how positive a conversation on mental health can be."