NBC News – JOHANNESBURG, South Africa – As South Africa marked Nelson Mandela’s 95th birthday with a nationwide “day of service” on Thursday, the government announced that the anti-apartheid icon’s health was improving.

“Madiba remains in hospital in Pretoria but his doctors have confirmed that his health is steadily improving,” the government said in a statement, referring to Mandela by his clan name.

Mandela was spending his 41st day in a Pretoria hospital with his family, who were celebrating his birthday with him. July 18 has become known as “Nelson Mandela International Day,” since the United Nations proclaimed it so in 2009.

“It’s an honorable day for us because it’s our grandfather’s birthday, so it’s literally a call for the whole world to go for service and to do something special,” granddaughter Zaziwe Dlamini Manaway said.

Students work in a public park in Cape Town on Thursday in honor of Nelson Mandela’s 67 years of public service.

“It’s basically a call for action for the whole world to do something for 67 minutes, to be selfless to do something to better someone else’s life someone else’s cause.”

The idea for a day of service was inspired by Mandela himself, in a speech celebrating his 90th birthday in London’s Hyde Park in June 2008.

Then, he told an adoring crowd: “It is the time for new hands to lift the burdens. It is in your hands now.”

The challenge is for everyone, worldwide, to spend at least 67 minutes doing something to help others, according to the Mandela Center of Memory, the foundation that guards his legacy. Mandela spent 67 years of his life struggling to transform the world, first as a human rights lawyer, then as an activist, then prisoner of conscience and eventually as the first democratically elected president of South Africa.

A newspaper vendor displays the front page of the Daily Sun in Soweto, wishing former South African President Nelson Mandela a happy 95th birthday.

He retired from public service in 2004. According to the center, Mandela has made it clear that he wants his legacy to be, “a living legacy of volunteerism and public service.”

President Jacob Zuma also paid tribute to Mandela and his work.

“On behalf of the government and all the people of South Africa, we wish Madiba a joyous 95th birthday,” Zuma said in a statement. “We are proud to call this international icon our own as South Africans and wish him good health.”

In spite of this upbeat note, this year’s celebration will be extremely poignant. For weeks now, there has been tremendous anxiety that Mandela might not survive until his next birthday.

Near Johannesburg on Monday, several of Mandela’s children and grandchildren helped paint and repair a shelter for abused women and girls.

“Of course he would love this,” his daughter Zindzi Mandela said, taking a moment from the work at hand. “It’s all about humility and compassion, which are key aspects of his character,” she added.

Everywhere, the family gets asked, “How is Madiba doing?”

Lately, the responses have been increasingly upbeat and hopeful, with Zindzi offering the most promising assessment yet on the eve of her father’s birthday. She said he has made “dramatic progress,” and that she expects him to be discharged from the hospital, “anytime soon.”

“It hasn’t been easy, Madiba isn’t young anymore,” she said at the women’s shelter. “But he’s in the best hands, and he’s a fighter, and he still has a charming smile.”

For the nation and Mandela’s admirers around the world, it will be a day of non-stop events, big and small.

Zuma was set to launch a new housing program for low-income residents near the capital, Pretoria. It’s a project in keeping with this year’s broad targeted concerns: food, housing security and literacy.

The Mandela family plans to gather by Madiba’s hospital bedside for a traditional birthday lunch. Many have said in recent days that this is a time to celebrate his heroic life.

Click here to read more.