Video report by ITV National Editor Allegra Stratton
Theresa May has vowed to abolish the "completely unacceptable stigma" around mental illness and transform the way the issue is addressed.
In her first speech on mental health, the prime minister announced:
Secondary schools will be offered mental health first aid training
New trials to strengthen links between schools and local NHS mental health staff
A major review of children and adolescent mental health services, led by the Care Quality Commission
Since Oli Regan was nine he has had mental health problems.
"I was going mad inside, literally. It was like being inside a prison in your head," he said.
But he was not diagnosed until some 15 years later - and in that period tried to take his own life four times.
"Then, that was the best thing to do. In my eyes, I was a burden to everyone else.
"When you're losing the will to live, you don't want to be waiting then to be put to the wrong person or for them not to have the funding for you.
"That's happened to me. I've still not had any therapy yet."
Mental illness is estimated to cost the country around £105 billion.
And one in four people has a common mental disorder at any time, according to the Government.
Last year David Cameron announced a plan to spend around £1 billion on mental health care over five years.
But today only an extra £15 million was added to the pot.
The prime minister set out plans as part of her vision of a "shared society", with an increased role for the state in addressing issues of social injustice.
The measures also include a green paper on support for children and young people and a further £15 million to provide alternatives to hospital visits, such as crisis cafes and community clinics.
There will also be an expansion of digital services and a review of the debt form system, which can see some cash-strapped people charged up to £300 by a GP to provide proof to creditors they have a mental illness.
Mrs May said: "For too long mental illness has been something of a hidden injustice in our country, shrouded in a completely unacceptable stigma and dangerously disregarded as a secondary issue to physical health.
"Yet left unaddressed, it destroys lives, it separates people from each other and deepens the divisions within our society.
"Changing this goes right to the heart of our humanity; to the heart of the kind of country we are, the values we share, the attitudes we hold and our determination to come together and support each other."
Training for schools
The focus on schools is driven by figures showing over half of mental health problems start by the age of 14 and 75% by 18.
Under the plans, mental health training for teachers and staff will be rolled out to a third of secondary schools in England next year, with the remaining two-thirds of secondary schools offered the support in the following two years.
Review of workplace practices
Mental health campaigner Lord Stevenson of Coddenham and the charity Mind's chief executive Paul Farmer will lead a review of workplace practices.
The government will consult employers, charities and legal experts to gather evidence about discrimination protections for workers with mental ill-health.
There is currently protection when problems persists for a year or more and are classed as a disability, but for many common disorders such as depression the average length of illness can be much shorter.
Mind chief executive Mr Farmer said: "Mental health should be at the heart of government, and at the heart of society and communities - it's been on the periphery for far too long."
Sir Ian Cheshire, the chairman of mental health campaign Heads Together, said: "The prime minister's announcements today are extremely important and very welcome, as they show both a willingness to tackle the broad challenge of mental health support and a practical grasp of how to start making a real difference."
Shadow mental health minister Barbara Keeley said: "This Tory government's record on mental health is one of failure.
"They might talk about equality between mental and physical health, but we are yet to see their rhetoric become reality.
"The government has failed to provide sufficient funding for mental health services, and people are being let down as a result."