Millions of South Africans are celebrating the 93rd birthday of the former President Nelson Mandela.

Mandela Day was inaugurated in 2009 on Nelson Mandela's birthday, July 18, and declared an international day by the United Nations in November 2009. Mandela Day was inspired by a call made by this world icon for the next generation to take on the burden of leadership in addressing the world's social injustices.

As a result, people around the world have been asked to mark the occasion by devoting 67 minutes of their time to work in their local community or one minute for every year of Mandela's public service.

As Mandela spent the day with his family in his home village of Qunu in the south of the country, thousands of of schoolchildren sang a special version of "Happy Birthday" to honor the leader.

Mandela spent 27 years in jail before he was released in 1990 and subsequently served one term as president from 1994 to 1999.

Throughout his political career, the former leader has reiterated several times that "it's in our hands" to create a better world and has insisted people can take inspiration from his example to take responsibility for themselves and to action their responsibility to others.

Despite years of struggle and imprisonment, Mandela remained optimistic and once famously said, "I am fundamentally an optimist. Whether that comes from nature or nurture, I cannot say. Part of being optimistic is keeping one's head pointed toward the sun, one's feet moving forward. There were many dark moments when my faith in humanity was sorely tested, but I would not and could not give myself up to despair."

As a result, in South Africa, many organisations, companies, NGOs and individuals have come up with activities they will set up on this day, inspired they say by Mandela's vision and claim that that small steps can help build a better world.

Local politicians also vowed to do their 67 minutes of volunteer work and many contributed their views on Mandela's ability to inspire others.

Also, leaders from all over the world have also joined in, and complimented the world known figure.

"Politically a person who had done an incredible amount of reading in prison and understood South Africa, someone who was also overwhelmed by the notion that he could never break up South Africa, that we had to keep it together, whatever the cost," noted former Speaker of South African Parliament Dr Frene Ginwala. "Mandela also had a kind of Gandhian belief that if what you were doing what was right, the right thing would happen."

In a statement, President Barack Obama said the South African leader was "a beacon for the global community and for all who work for democracy, justice and reconciliation," and praised him for devoting his life to public service and a legacy that exemplifies what "wisdom, strength and grace."

While UN secretary-general Ban Ki-moon said: "The best way we can thank Nelson Mandela for his work is by taking action for others and inspiring change."