Young people are experiencing a "double epidemic" of obesity and mental health problems, the head of NHS England has warned.
Chief executive Simon Stevens said the issues were key priorities as the health service, which is marking its 70th year, looks to the future.
But he said technology companies and social media giants share responsibility for addressing the mental health issues affecting children.
In his keynote address at the NHS Confederation annual conference in Manchester, Mr Stevens said the NHS was having to confront a "double epidemic affecting our children".
"It is obvious that there is more unmet need for young people's mental health services than probably any other part of the health service," he told the audience.
"The conversation, though, around young people's mental health has got to be wider than just about what the NHS can do.
"This is certainly about schools, but we also have to ask some pretty searching questions around the role technology companies, social media, and the impact that that is having on childhood.
"So, this cannot be a conversation that is simply left to the National Health Service to pick up the pieces - for an epidemic of mental health challenge for our young people induced by many other actors across our economy."
Mr Stevens said the NHS must "lock in" progress on cancer and mental health and also prioritise the integration of social care as it considers plans for the next five to 10 years.
Obesity was also highlighted as a key issue for the health service.
"It is absolutely true that we need to be more physically active," Mr Stevens said.
"But that by itself is not going to deal with what's happening to our food and drink calorific environment.
"That said - here is a key fact for you - on average in this country we spend twice as much time on the toilet than we do exercising."
Prime Minister Theresa May has pledged a long-term funding settlement for the NHS, which celebrates its 70th anniversary next month.
Mr Stevens told the audience he was "heartened" by the commitment to securing a deal.