Today, Bono, the U2 singer, global activist and one of the most powerful leaders on the world stage, turns 50. At this important milestone, it is worth briefly taking stock of his journey thus far—a journey of purpose, impact, passion, and humor. It is a path with lessons for leaders from all walks of life.

Let’s begin by considering all the roads Bono (who was born Paul David Hewson in Dublin) did NOT take as he has traveled these last five decades. He has never been the CEO of a major company. He has never held public office or scored a big campaign contribution. He did not graduate from an elite university. He did not make most of his considerable wealth in the global equity or debt markets.

So what has Bono been up to that accounts for his enormous influence—influence that extends from the 100,000-seat stadiums that U2 plays to the White House, Vatican, and Downing Street to debt forgiveness and medical aid to Africa? After all, he was not born with cash or connections. His father, Bob Hewson, who was a postal worker, used to tell him not to dream so he would not be disappointed. So how did a curious, restless boy whose mother died when he was 14, leaving him with what he later called a “God-shaped hole” at his core, become a leader who could convince Bill Clinton, George W. Bush, and Jesse Helms to increase America’s aid to Africa more than fourfold, from around $2 billion in 2000 to $8 billion in 2009? Whose Global Fund has committed $19 billion to fighting AIDS, tuberculosis and malaria in 144 countries?

Bono’s leadership journey has its roots in U2, the Irish band that he and several schoolmates, including Larry Mullen, Jr., David Evans (who later became known as “The Edge”), and Adam Clayton, founded in 1976. The story of U2’s success is one of commerce as much as art. At its center is the creation and stewardship of a very powerful brand, a brand that, in the midst of an ongoing perfect storm of turbulence in the music distribution business, is still going strong around the world.

Another important part of U2’s success has been the very profitable business model that the four musicians and their savvy manager Paul McGuiness have developed. It is a model that keeps evolving—usually a step or two ahead of the gales of creative destruction buffeting the larger industry—and one that has benefited from a lot of experimentation, ongoing reinvention, and a consistent willingness to challenge industry standards.

But brands and business models are only as good as the product and people behind them. The U2 team, including musicians, management, administrative staff and others, is a vibrant, highly productive organization focused on producing relevant, world-class offerings—from CDs to stadium tours to films—that sell briskly in virtually every market on earth. Worldwide, the band has sold more than 140 million records. Its 2005 “Vertigo” tour grossed $389 million, second only to the Rolling Stones for a single-tour gross.

Leading this enterprise has meant keeping the key team members motivated, engaged and growing—as human beings as well as music makers—for almost 34 years. Growing the organization four gangly teenagers - who in 1979 had to sell one of their instruments in order to buy passage home after a short London tour—to one of the most successful rock bands in history has demanded abiding faith, a steady stream of courage, huge reserves of personal energy, and a disciplined openness to the world as he continues to meet it.

From this solid foundation, Bono has acquired great agency. Not only money for himself and sway with his customers—music fans of all ages, shapes and sizes—but also extraordinary access to other movers and shakers as well as influence on a wide range of issues outside rock music. One of the most compelling aspects of Bono’s leadership is how he has chosen to use the authority that has accompanied business success. He has decided, over and over again, to put his artistic, political, strategic, and spiritual muscle to work to alleviate suffering in the world’s poorest countries.

He talks a lot about justice as animating his work and spirit. But this is perhaps too abstract a term for what Bono seems to be doing on a daily basis. One of the most important things he does every day is to keep educating himself on the people, economies, and pressing problems of developing countries. Many of the experts, including the developmental economist Jeffrey Sachs, have commented on how thoroughly the singer-turned activist does his homework.

A second, important part of Bono’s days is leading a spectrum of organizations like the ONE campaign and RED that each advance his broader mission. This involves coordinating these groups and monitoring their progress. As of late 2009, the Global Fund had helped support antiretroviral treatment for 2.5 million people; helped provide 105 million HIV counseling and testing sessions; and helped finance 4.5 million instances of basic care and support services for orphans and vulnerable children. Bono’s leadership also involves selling these organizations and their work to all kinds of stakeholders.

Amidst all this activity, Bono keeps turning his energy to making and distributing music. This is part poetry, part packaging for the band and himself (he once said he had to learn how to be a rock star), part dollars-and-cents, and part competitive drive. His work as a musician is as central to his humanitarian efforts as the money he helps raise or the politicians he wins over for debt relief. At the same time, his activism has become part of the U2 brand, animating the way that millions of people think about the group and their offerings.

Herein lie several lessons. First, all successful organizational leaders—from presidents to police chiefs to CEOs—wield power, often in excess of that granted them by their office. How such individuals decide, explicitly or not, to use this control is a question of grave importance for the world today. The most important problems confronting us now, including a precarious global financial system and an equally vulnerable environmental system, do not come in separate buckets labeled “business” and “public policy.” These are challenges that are smashing through older boundaries and helping redefine organizational place and mission.

Second, as Bono seems to understand, these issues demand a new kind of leadership, one based not in aging hierarchies and status systems but in humility, an ardent desire to learn and a respect for the individuals that organizations serve.

Third, individual leaders have to keep getting right with themselves about their own path and impact.

Finally, effective leadership today demands a willingness to stay open, not only to one’s own enterprise but also to the teeming global village around it. Bono, like Abraham Lincoln 150 years ago, has not let himself become isolated in an elite atmosphere. He has used his touring and travels as classrooms to help him understand the hopes, dreams and tribulations of his fellow citizens, whom he often calls his brothers and sisters. And he has used this knowledge to light his way, his music and his leadership.

Happy Birthday, Bono.