Video report by ITV News correspondent Paul Davies
Former England cricket captain Andrew Flintoff, rapper Professor Green and Tony Blair's former spin doctor Alastair Campbell are some of the stars talking publicly about their mental health battles in a series of new films.
The Duke and Duchess of Cambridge and Prince Harry have released the 10 films that feature celebrities and ordinary people describing the life-changing conversations where they opened up about problems such as anxiety or depression.
Speaking about the films, the royals said: "Since we launched Heads Together last May, we have seen time and time again that shattering stigma on mental health starts with simple conversations.
"When you realise that mental health problems affect your friends, neighbours, children and spouses, the walls of judgment and prejudice around these issues begin to fall.
"And we all know that you cannot resolve a mental health issue by staying silent.
"Attitudes to mental health are at a tipping point. We hope these films show people how simple conversations can change the direction of an entire life."
The royals commissioned the #oktosay films - directed by leading figures such as My Beautiful Launderette creator Stephen Frears - as part of their Heads Together mental health campaign which aims to encourage people to talk about their psychological issues.
Professor Green speaks to ITV News Presenter Alastair Stewart:
In one film former England cricket captain Andrew Flintoff speaks to rapper Professor Green about how he "ran away" from depression, leading him to drinking and "living differently".
Rather than people turning their backs on him as he feared they would if he opened up about his depression, but that instead it was the "complete opposite" and helped other people open up to him about their feelings.
He added: "The hardest thing for me initially was talking. I'm not a big talker. I'm from the north of England, from a working-class family. We don't talk about our feelings."
In another film, Tony Blair's former spin doctor Alastair Campbell talks to his partner Fiona Millar about his well-documented fight against depression.
Mr Campbell reveals how he felt he was "going insane" and was so distressed that at one point he began hitting himself in the face.
Ruby Wax reveals in another film that only by talking to other people with depression does she truly feel "understood" and "relieved", which help her to "heal".
Earlier in 2017 Heads Together commissioned a YouGov poll which found that 80% of people who have talked about their mental health have found the conversations helpful.
Speaking ahead of the launch of the films, Professor Green, real name Stephen Manderson, who suffers from anxiety, said it was important for public figures to be honest about their issues.
"The problem with a lot of mental health issues - depression, anxiety, anything - is it becomes insular and you feel like you're the only one suffering with it and because you don't talk to someone about it, you don't ever realise you're not.
"So if I was to have heard someone like (American rapper) Biggie who I idolised open up and talk about something that he went through like that...it would have made it more okay."