Now, some have said I blame too many problems on my predecessor, but let's not forget that's a practice that was initiated by George W. Bush.

David [Cameron] has been an outstanding friend and partner on the global stage and, based on our conversation, I'm confident that the UK is committed to an orderly transition out of the EU.

As I got older, then my particular ambitions started cohering around creating a world in which people of different races or backgrounds or faiths can recognize each other's humanity, or creating a world in which every kid, regardless of their background, can strive and achieve and fulfill their potential.

I think that America has to stand with democracy.

The Iranian regime supports violent extremists and challenges us across the region. It pursues a nuclear capability that could spark a dangerous arms race and raise the prospect of a transfer of nuclear know-how to terrorists. Its president denies the Holocaust and threatens to wipe Israel off the map. The danger from Iran is grave, it is real.

America is an unlikely place - a country built on defiance of the odds; on a belief in the impossible. And I remind you of this because as you set out to live your own stories of success and achievement, it's now your turn to help keep it this way.

So don't get cynical. Cynicism didn't put a man on the moon. Cynicism has never won a war, or cured a disease, or built a business, or fed a young mind. Cynicism is a choice. And hope will always be a better choice.