The Duke of Cambridge urged the nation's young to speak out about their mental health problems after hearing the moving story of a suicidal man saved by a Good Samaritan.
William, with wife Kate, told a group of 14 and 15-year-old students invited to Kensington Palace that he felt "we don't listen, we don't talk enough" and called on them to be there for each other.
The south London school pupils had listened intently as mental health campaigner Jonny Benjamin, 29, described how, when a drama student, he was saved from throwing himself off Waterloo Bridge by passer-by Neil Laybourn, 33, a private fitness instructor.
Years later, Mr Benjamin started the #FindMike search in 2014 to track down the unknown passer-by who stopped him killing himself in 2008.
Then 20, he had been diagnosed with a combined schizophrenia and bipolar condition and said he felt his life had hit ''rock bottom'' before the intervention of a stranger, later identified as Mr Laybourn when the search went viral.
Earlier, the Cambridges heard the same heartfelt story from the two men during a meeting at St Thomas' Hospital, where Mr Benjamin was sectioned after he walked away from the edge of the bridge.
The Duke told the year 10 and 11 pupils from Dunraven secondary school in Streatham that hearing the men's story was "very eye-opening".
The royal couple had joined a discussion the teenagers were having with the men after the youngsters watched a documentary about the pair.
William added: "If I may add anything to the expertise of what Neil and everyone here is talking about - it's the importance of talking to each other.
"(I) really feel that we don't listen, we don't talk enough, so I hope if anything you take away from today, it's talk amongst yourselves, share your problems, and communicate and be there for each other."
The Cambridges, who have consistently worked to highlight the issue of mental health, spent the day focusing on the issue of suicide with public and private engagements, to shine a light on support for those thinking of taking their own lives.
William, who has been called out to several suicide attempts in his job as an air ambulance pilot, wants to focus on getting better care for young men with suicidal thoughts as part of a joint crusade on mental health with Kate and Prince Harry.
During his meeting at St Thomas' with the mental health campaigner and his Good Samaritan, William said: "Someone told me five people a day try to kill themselves. I was just blown away by the statistics."
Sitting beside Kate on a sofa talking to the two men, he added: "For both of us, the mental health piece has got lots of aspects. It's such a big issue that we need to do something about it.
"We feel it's been raised higher up the ladder. It's suddenly bubbling just under the surface. Now we need to get up to the next level, to the surface."
He plans to focus on male suicide, while Prince Harry concentrates on mental health issues facing military veterans, and Kate spends much of her official work on highlighting what needs to be done to help children affected by problems such as family breakdown, domestic violence, and addiction.
The Duchess, in a green Erdem coat, stressed that childhood problems were the root cause of many of the afflictions of adults.
"We see through the work that we do with addiction, homelessness and knife crime that a lot of it stems back to childhood," she said.
Last month figures from the Office for National Statistics revealed a 3% rise in suicides in England, though the numbers fell in Scotland, Wales, and Northern Ireland. Altogether 6,122 people died by suicide in 2014 in the UK, down from the 6,242 who took their own lives in 2013.
Mr Benjamin told William and Kate during their chat earlier in the day: "Suicide is still a massive taboo," and when the Duke asked why, he replied: "It's the shame and the embarrassment."
Turning to Mr Laybourn, who is now a close friend, he said: "When I met you on the bridge it was the first time I'd ever opened up and used that word - suicidal - because I was so ashamed and embarrassed.
"I was 20 and everybody was saying to me you should be having the best time of your life, and I was at uni and I was obviously struggling but I couldn't say that because I was too embarrassed.
"I was about 16 when I started hearing voices in my head, what I thought was the devil, I was so embarrassed, I kept saying to myself - you should not be feeling this way."
Mr Benjamin later told the secondary school pupils that struggling with being gay had also been a major issue with his mental health.
The Duke and Duchess began their day with a private visit to the Maytree Suicide Respite Centre in Finsbury Park to meet its small team of staff and volunteers and some former residents.
After listening to the discussion with young people at Kensington Palace they met a group who had experienced a family member or friend committing suicide.