The success of the NHS is down to the "brilliance" of its staff, chief executive Simon Stevens said as the institution celebrates its 70th anniversary.
Mr Stevens paid tribute to the 1.5 million doctors, nurses, ambulance staff, therapists, porters, caterers and others who, along with volunteers, make up the biggest care team in the world.
His message, filmed in an ambulance control room, came as the country marks 70 years of the NHS.
The day of celebration will see scores of buildings across the country - from the Eden Project in Cornwall to the Houses of Parliament, as well as the London Eye and Everton Football Club's Goodison Park - lit up in the NHS's trademark blue in a nod to the much-loved service.
Thousands of Big 7Tea events are taking place across England to thank staff and raise awareness of NHS charities, while services will take place at Westminster Abbey and York Minster to pay tribute to NHS staff and patients.
Participants in the Westminster Abbey service include Freya Lewis, a survivor of last year's Manchester terror attack, who has undergone more than 60 hours of surgery and had to learn to walk again, and Dr Martin Griffiths, a leading NHS trauma surgeon who led a team treating victims of the London Bridge terrorist attack.
Singer Linda Nolan, who is being treated for breast cancer, will host a choral concert at York Minster. She will be joined by 15-year-old Eve Senior, a survivor of the Manchester attack who wants to become a nurse, and as Amen Dhesi, who became a carer at 13 for his father who has bipolar disorder.
Ethel Armstrong, an 87-year-old former nurse cadet and radiographer - who was working in the NHS on its first day and who has gone on to give it seven decades of service throughout her working life and into retirement - will be running the @NHS Twitter account.
Mr Stevens said: "Today we're marking the 70th birthday of the National Health Service.
"It's a time for celebration looking back over seven decades when we're all living a lot longer and healthier - more than 10 years extra.
"We've seen amazing medical advances, whether it's organ transplantations or new cures for cancer or vaccines.
"But the reason why the health service does so well is frankly due to the brilliance of the staff."