Kate Middleton stuns in Oscar de la Renta as she and Prince William make passionate plea for mental health awareness

February 6William and Kate (who wore a magenta dress by Oscar de la Renta) arrived at the Guild of Health Writers Conference with Heads Together. Will and Kate, who along with Harry, launched the campaign to merge mental health charities encouraging people to speak out and end the stigma behind mental health issues. Photo: Eddie Mulholland-WPA Pool/Getty Images

William warned that "silence can kill" during his speech. The Prince encouraged people to seek help and speak out about the issues before it's too late. "I got interested in mental health for another reason," the Prince told the crowd. "One that was related to my work as an Air Ambulance pilot. It was suicide, a subject that is so often hidden. The suicide rate among young men in this country is an appalling stain on our society. Suicide is the biggest killer of men under 40 in this country. Not cancer, not knife crime, not road deaths – suicide. If one of these other issues took so many young lives, there would be a national outcry. But there has only ever been silence. And this has to stop. This silence is killing good people." Photo: Eddie Mulholland-WPA Pool/Getty Images

Will and Kate spoke to guests during the Guild of Health Writers Conference with Heads Together, which primary focus was on anxiety. The royal continued in his speech: "For Catherine and Harry, their journeys to Heads Together were different: Harry predominately through his work with veterans, and Catherine through her work with children and young families. But their conclusions were the same – that mental health needed to be brought out of the dark and de-stigmatised." Photo: Twitter/@kensingtonroyal

William spoke to Louise and Ryan, a couple who are participating in the London Marathon for Heads Together. During his speech, William mentioned the importance of Heads Together and the marathon's partnership. "This gives us an incredible platform to start millions of conversations on mental health and make this year's London Marathon the first ever 'mental health marathon,'" he shared. "We want to get the country talking about mental health." Photo: Twitter/@kensingtonroyal

As part of their Heads Together campaign, Prince William and Kate Middleton attended the "Place2Be Big Assembly" held at Mitchell Brook Primary School during Children's Mental Health Week earlier in the day. Place2Be is one of eight charities behind the Heads Together campaign led by the Duke and Duchess of Cambridge and Prince Harry.Photo: Karwai Tang/WireImage

The Duchess of Cambridge, who is a patron of Place2Be, looked radiant stepping out for the engagement in a red skirt suit by Luisa Spagnoli, marking the fourth time she has worn the stylish ensemble. Kate accessorized the look with a Mulberry clutch and black suede Gianvito Rossi pumps.Photo: Max Mumby/Indigo/Getty Images

The mom-of-two was in her element as she chatted with children at Mitchell Brook Primary School.Photo: Max Mumby/Indigo/Getty Images

William received a sweet drawing of himself and Kate from the excited children, who gathered to see the royals.Photo: Karwai Tang/WireImage

The Duke and Duchess participated in a discussion with students from the school on how kindness can help individuals through difficult times.Photo: Ian Vogler - WPA Pool/Getty Images

Kate delivered a speech encouraging children to help each other. She said, "My parents taught me about the importance of qualities like kindness, respect, and honesty, and I realize how central values like these have been to me throughout my life. That is why William and I want to teach our little children, George and Charlotte, just how important these things are as they grow up. In my view it is just as important as excelling at maths or sport." Photo: Twitter/@KensingtonRoyal

Nadia Dhicis, ten, joined the royals on stage, where she was presented with the first Place2Be 'Kindness Cup' for showing exceptional kindness in her community.Photo: Ian Vogler - WPA Pool/Getty Images

February 5Prince Harry, Prince William and Kate Middleton showed off their competitive side, while out at a Heads Together London Marathon Training Day. The royals were joined by about 150 runners who are training for the London Marathon at the Queen Elizabeth Olympic Park.Photo: Karwai Tang/WireImage

Meghan Markle's boyfriend stretched prior to racing his older brother and sister-in-law in a relay race. Meanwhile William joked to his teammates grabbing his thigh saying, “Oh, my hamstring.” Photo: Karwai Tang/WireImage

William had the eye of the tiger! The Duke gave his wife a high five before they competed against each other in a race. Photo: Karwai Tang/WireImage

Run Kate, run! The Duchess showed off her sporty side as she raced her husband and brother-in-law at the Team Heads Together London Marathon Training Day. While she came in third, the mom-of-two looked stylish wearing a quilted down ski jacket by Perfect Moment and New Balance sneakers.Photo: Max Mumby/Indigo/Getty Images

Following the race, which Harry ultimately won, William playfully told his wife, "You nearly beat me!”Photo: Karwai Tang/WireImage

Prince Harry peered over his shoulder as he took the lead in the royal race.Photo: Chris Jackson/Getty Images

No surprise Harry, who has raced the fastest man in the world, Usain Blot, came in first place, while his brother followed in second.Photo: ALASTAIR GRANT/AFP/Getty Images

The royal couple shared a rare moment of affection on the track at the Queen Elizabeth Olympic Park.Photo: Karwai Tang/WireImage

Prince William cheered as he held on to his wife.Photo: Max Mumby/Indigo/Getty Images

Prince George's parents shared a laugh at the Heads Together event in London.Photo: Max Mumby/Indigo/Getty Images

The royal trio spoke to team members about preparations for the 2017 race and how they can help turn the event into the “mental health marathon.” Photo: Karwai Tang/WireImage