"Tata (father) is still with us, very strong... very courageous, even, (for) lack of a better word, on his death bed. I think he's still teaching us lessons," Mandela's oldest surviving child, Makaziwe Mandela, told public broadcaster SABC.
"Lessons in patience, lessons in love, lessons in tolerance."
Mandela, 95, is currently under medical care at his Johannesburg home after spending nearly three months in hospital with a lung infection earlier this year.
"Every moment, every minute with Tata amazes me and there are times when I have to pinch myself that I come from this man who is so strong, who is a fighter," said his daughter, speaking at the launch of the Nelson Mandela Opus, a massive book about his life and journey from anti-apartheid fighter to icon of reconciliation.
"Even when there are moments when you can see he's struggling, but the fighting spirit is still there with him."
Last month, President Jacob Zuma described Mandela's condition as "stable but critical" after paying him a visit.
"He's still with us. Even when there are moments when you can see he's struggling but the fighting spirit is still there with him," his grandson Ndaba Mandela said Tuesday.