One of my great personal regrets is not having better preserved the autograph I received from President Kennedy when I had the overwhelming good fortune to meet him as a nameless teenager from a dusty village in Korea.

I was in the United States as part of an eye-opening tour organized by the Red Cross for a group of young people from around the world. It was more than a visit to a foreign country – it was a pilgrimage to the land of possibility, a shining democracy that had helped to save my nation in its darkest hour.

President Kennedy’s signature was quickly dispersed among the many fingerprints of my friends who grabbed at the glossy White House Bulletin and passed it around with such eagerness that by the time it returned to me no trace of his writing remained.

But nothing could remove the imprint the American President made on my life. Meeting him was a turning point. His words that day in the South Lawn sparked my decision to become a diplomat and dedicate myself to public service.

As he looked out at our diverse group representing countries that were then on different sides of the Iron Curtain, President Kennedy reminded us that we could be friends even if our governments were not. And he said the words I chose to live by: “There are no national boundaries; there is only a question of whether we can extend a helping hand.”

As I grew older and progressed through my career in national diplomatic service, that idea came into sharper focus, and I resolved to contribute to the global public good. As Secretary-General of the United Nations, I try my best to serve the peoples of the world in whose name the Organization’s Charter was adopted.

President Kennedy had great faith in the United Nations. His last speech to the General Assembly just weeks before his death reads like a primer for addressing the problems that still plague us today. He stressed the indivisibility of human rights. He opposed wasteful military spending. He called for racial and religious tolerance. He praised United Nations peacekeeping. And he insisted that we embrace peace not only on paper, but in our hearts. These are all values I defend along with a corps of dedicated United Nations staff members around the world.

In my own encounters with the world’s young people, I try to deliver the message that JFK gave to me: Be a global citizen and love your country by serving the world.

Soon after I became Secretary-General, Senator Edward Kennedy came to visit. He brought me a framed copy of the photograph of our group on the South Lawn along with President Kennedy’s speech that day. I was deeply touched by Sen. Kennedy’s understanding of how much I treasured my encounter with his brother.

Reflecting on President Kennedy’s tragic death a half century ago, I realize perhaps I should revise my regrets over losing his autograph. That signature had not simply faded off the paper into a void; it had been absorbed into the skin of my friends thanks to their enthusiasm. I hope to continue spreading the message of this man, who held fast to high ideals and placed such faith in the United Nations, to all people, especially the world’s youth.

Ban Ki-moon is the United Nations Secretary-General.