As secretary-general of the United Nations, I have more stamps in my passport than I can count, but there is none that I treasure as much as the first one.

"United States of America," it said. The date: August 1962. I was a wide-eyed 18-year-old from a rural village in war-shattered Korea. The American Red Cross had invited me to join 112 teenagers from 42 countries to travel across the United States visiting Red Cross chapters, meet each other and learn the value of service. It was an incredible privilege.

As soon as I stepped off the plane, I was overwhelmed by the warmth of the people. The wealth and plenty was a cultural shock to a very poor boy from devastated Korea. But what moved me most was the spirit of helping others I witnessed from small-town America to the capital.

We met President John F. Kennedy in the Rose Garden. He noted that we came from countries where the governments may not get along, but people do. He said he placed great hopes in us. It was at that moment that I resolved to embark on a life of public service. That journey that began 50 years ago continues to this day at the United Nations.

Half a century later, the importance of reaching out across boundaries to help others is more critical than ever. In this digital age, where people can connect with a click, everyone has the potential to make a difference.

Earlier this month, I had the opportunity to meet Beyoncé Knowles. She is well-known as a singer, actress and all-around superstar, but I met a global humanitarian lending her spotlight to the work of the United Nations. Her song, "I Was Here," is dedicated to World Humanitarian Day, an occasion to pay tribute to those who have given their lives for the cause and to support those who carry out vital, life-saving work around the world.

This year, we launched a campaign for people to take action. Across generations and continents, they replied with initiatives to help those in need.

Thanks to the immense power of social media, these acts of service were shared globally, inspiring countless others to carry out their own good deeds.

It was a clear reminder of the lesson I first learned 50 years ago and still live by today: Engaging in the world is the best path to a better future.

Individual acts of service may seem small, but each reverberates far beyond the people who are directly affected, generating a momentum that builds to protect our world.

At a time when extremists are exploiting national, racial and religious differences in new deadly ways, we must never forget the importance of our common humanity.

The United Nations is addressing global challenges such as insecurity, injustice and inequality. We succeed to the extent that this spirit of human solidarity is understood and practiced by governments and peoples. And we depend on our partners, such as the International Red Cross and Red Crescent movement, which share our common values and brave danger to uphold them.

In many cases, the Red Cross is the last hope in the most hazardous, conflict-stricken areas where even U.N. humanitarian workers cannot travel.

Today, the United Nations and the Syrian Arab Red Crescent are working together to bring aid to the suffering people of Syria.

In crisis spots around the world, we work together to save lives, protect human rights and promote dignity.

My own 50-year journey will come full circle this month as that original international group of Red Cross student leaders gathers together for a reunion. With all the changes we have experienced, President Kennedy's words to us remain as true as when we first heard them: "There are no national boundaries; there is only a question of whether we can extend a helping hand."