JOHANNESBURG – Michelle Obama on Wednesday told young African leaders, including members of South Africa’s post-apartheid generation, that there are more causes worth fighting for and more history to be made. She urged them to be the ones who end hunger, wipe out HIV/AIDS and protect women’s rights.

In an emotionally stirring speech at a church that became a popular refuge during the fight against government-imposed segregation in South Africa, America’s first lady drew on the struggle for racial equality in the U.S. and in this country as she sought to inspire young people to become the next generation of problem-solvers.

“I know that as your generation looks back on that struggle and on the many liberation movements of the past century, you may think that all the great moral struggles have already been won,” Mrs. Obama said in a keynote address to a U.S.-sponsored leadership conference for more than 70 young African women. “But while today’s challenges might not always inspire the lofty rhetoric and high drama of struggles past, the injustices at hand are no less glaring. The human suffering is no less acute.

“So make no mistake about it: There are still so many causes worth sacrificing for. There is still so much history yet to be made,” she said.

Sixty percent of Africa’s population is under age 25 and two-thirds of South Africans are younger than 30, Mrs. Obama said.

The first lady said this generation can be the one that brings prosperity to forgotten corners of the world, banishes hunger from Africa and ends HIV/AIDS and the stigma associated with it. She said they can ensure that women are no longer treated as second-class citizens, that girls get an education and that any type of violence against women is seen as a violation of human rights.

She received an effusive introduction from Graca Machel, the wife of former South African President Nelson Mandela, who said Mrs. Obama is the “queen of our world.”

That welcome, which included music from a choir whose members wore colorful Zulu hats, was so rousing that Mrs. Obama was visibly moved by the time she got to the microphone. She shook her head as if in disbelief, crossed her arms over her chest and thanked the audience of 2,000 for that “almost overwhelming” introduction. A large television screen aired the speech to a nearby park.

In her remarks, Mrs. Obama told Africa’s youth to reject the “false comfort” that they shouldn’t be concerned about the suffering of others and to not get impatient over the slow pace of change. She told them to not underestimate their power to make a difference and suggested that they think of one another’s accomplishments when self-doubt starts to creep in.

She said she was thinking about the young activists who met at the American Library in Soweto during the apartheid era to read Martin Luther King Jr.’s speeches and about students on U.S. college campuses, including her future husband, who planned boycotts to support students in South Africa.