President Jacob Zuma visited the anti-apartheid leader Wednesday evening.
"We are encouraged that Madiba is responding to treatment and urge the public to continue providing support and showering him with love which gives him and the family strength," Zuma said in a statement that referred to Mandela by his clan name.
Mandela was hospitalized June 8 for what the government said was a recurring lung infection, and his condition has been critical for over two weeks.
The Nobel Peace Prize laureate's 95th birthday is on July 18 and his foundation's Twitter feed is asking people to join in the volunteer-day initiative.
The goal of Mandela Day is to inspire individuals to "take action to help change the world for the better." The movement asks people to donate 67 minutes of their time in reflection of what the foundation says is the more than 67 years Mandela spent serving his community, his country and the world.
The foundation's Twitter feed often shares quotes from the man who became South Africa's first democratically elected president after spending 27 years in prison for his fight against racist white rule.
One Mandela quote shared this week said: "Abject poverty is demeaning, is an assault on the dignity of those that suffer it. In the end it demeans us all."
South Africa has made great strides since its official policy of apartheid, a government policy that favored white South Africans. But great inequalities remain, fueling racial tension in the country.
"I would say what we're struggling with today is the gross inequalities that we've inherited that will take generations to overcome, and people are understandably resentful," Denis Goldberg, Mandela's friend who was jailed for two decades for fighting against apartheid said at an anniversary event this week.
South Africa President Zuma said last month that black South Africans continue to have less education and fewer skills than whites because of the apartheid era. As part of promoting national reconciliation, the implementation of black economic empowerment policies will continue, he said.