Incoming President Rodrigo Duterte had one of his tongue-in-cheek moments early Thursday morning in a press conference in Davao City.

Asked by a journalist about his health, Duterte nonchalantly replied, "I am dying, what's your problem?"

"Gusto ninyong malaman kung kailan ako mamamatay?" he asked. "Ano pa purpose magtanong ng ganoon...so that I cannot be a good president?"

The 71-year-old Duterte also issued a challenge to those who doubt his physical fitness.

"Punta tayo sa bahay ko, I will do the treadmill, 1-hour plus," he said. Kapag hindi ko kaya 1 hour [and] 30 minutes, kayo ang mag-resign sa trabaho. Sobrahan ko. If I falter, I resign."

He also told journalists in the same press conference not to take some of his statements seriously.

"I am enjoying my last days [as mayor]. Kaya kung preposterous [ang statement], kalabitin mo ang taga-Davao [and ask if I was joking]," Duterte said.

The mayor has repeatedly said there is nothing to worry about his health, noting that he has never lied about his medical condition.

Aside from a slipped disc, Duterte, a former smoker, admitted in an earlier interview that he has had Buerger's disease, a condition that causes constriction of blood vessels due to nicotine. He also suffers from Barrett's esophagus.

He has refused to disclose to the public his medical records. "No, no, no, I will not do that. Ayaw ko. Ano ako, buang (crazy)? Para ka tuloy na you're forcing yourself to say, 'I'm a liar,'" he had said.

Duterte, the Philippines' 16th president, will be its oldest ever chief executive and commander-in-chief. He has eight grandchildren.