“The day will come when I will become sick,” Mugabe, who is Africa’s oldest ruler, said in an interview on state-owned Radio Zimbabwe on the eve of his birthday.
“As of now I am fit as a fiddle.”
He poked fun at media reports about a life-threatening ailment.
“I have died many times,” he said. “That’s where I have beaten Christ. Christ died once and resurrected once. I have died and resurrected and I don’t know how many times I will die and resurrect.”
Mugabe’s health has been the subject of much speculation, especially since WikiLeaks last year released a 2008 US diplomatic cable saying central bank chief Gideon Gono had told then-US ambassador James McGee that Mugabe had prostate cancer and had been advised by doctors he had less than five years to live.
Mugabe, who has ruled Zimbabwe since independence in 1980, has repeatedly shot down rumours he is sick.
He visited Singapore several times last year, with his spokesman saying the president had gone for cataract surgery amid repeated media reports that he was suffering from cancer.
Mugabe’s health has been cited as one reason that a faction of his ZANU-PF party has pushed to rush new elections.
Mugabe has already been named as the party’s candidate for the polls, which he has said should be held this year.
He turned 88 on Tuesday and a birthday rally will be held at a stadium in the eastern border city of Mutare on Saturday.
The celebrations will include a football match by top league teams and a concert featuring the country’s top musicians.
On Tuesday, the state-run Herald newspaper carried 22 pages of messages congratulating the veteran ruler.