The Duke and Duchess of Cambridge and Prince Harry have made an impassioned plea for society to recognise that mental health problems are suffered by all and the sooner everyone reaches out to help the better.
William, Kate and Harry spoke out at a reception, organised by their Heads Together organisation, which recognised outstanding individuals who have helped friends, family or colleagues in need.
The royal trio also took a trip on the London Eye, marking World Mental Health Day by riding with guests who have suffered psychological problems and their supporters.
The Duke spoke first at the event at County Hall, telling the guests that mental health was "not a dirty word" and "we all have mental health like we do physical health, good or ill".
He added: "But not seeking help at those times when it all seems too much, or we are depressed or anxious, can impact the rest of our lives. Put simply, the three of us want to make asking for help no longer a big deal."
William, who is an air ambulance helicopter pilot, said: "Personally, in my work at the air ambulance, I see how colleagues and families help each other through traumatic moments.
"The three of us have learnt a lot in the past few months as we have met people. The conclusion we are coming to is that the more we all talk about this, the more collectively as a society we can do to support one another."
Heads Together, which is being spearheaded by the royal trio, aims to change the national conversation on mental well-being and is a partnership between charities that provide frontline mental health support.
Kate, who wore a dress by Kate Spade, spoke after her husband and echoed his words: "All of us know someone who has been through difficult emotional times, and we know how hard it can be to see a way forward.
"William, Harry and I feel it is our duty to do what we can, with your help, to shine a spotlight on emotional well-being and highlight the support that is out there to prevent or manage the pain at difficult times."
Harry spoke passionately about the issue, ending the speeches by saying: "It's not rocket science, but most of us don't know what to do if a friend or family member is suffering.
"Having some basic knowledge, and having the confidence to act on your knowledge, can make a huge difference to those around us."
He added: "As William said earlier, we all have mental health, just as we all have physical health. Too often we think mental health problems are things that happen to other people, not us.
"But we will all experience pressure on our mental health at some point during our lives. The more we accept that, the better we can help each other. Catching it and recognising it early saves lives."