Scott Morrison says he's been on his knees in tears over the difficult border protection decisions to turn back asylum seeker boats.
But the prime minister says he made tough calls because he didn't want Border Force agents to keep pulling dead children from the water.
"Politics is not for the faint-hearted, and you've got to be prepared to understand and own and carry the burden of decisions," he told a Lifeline event in Sydney on Friday.
"You'll find yourself on your knees, you'll find yourself in tears, you'll find yourself wrestling with this tough stuff."
He was asked if he'd been literally on his knees in tears over these issues, and the prime minister replied: "Of course I have. Why wouldn't I be? These aren't easy issues."
Mr Morrison said he went to refugee camps around the world when he was immigration minister, and said he was fully aware of the impact his decisions have had.
"There is no decision that you make in this space that is free of moral burden," he said.
"You cannot allow yourself a leave pass to think that there is.
"This job is not for people who can't confront this stuff."
The prime minister said he had prayed for the children in detention on Nauru and he hoped it had made a difference.
He said there were about 30 children still left on Nauru. There were more than 1300 children in detention on Manus Island and Nauru when the coalition took over from Labor in 2013.
"We closed 17 detention centres," Mr Morrison said.
"Our predecessors sent pregnant women to Manus Island, we didn't do that."
The coalition has been under internal and external pressure to get children off Nauru, and many have been resettled to the United States or brought to Australia for medical treatment.
But refugee advocates say children brought to Australia are in limbo because they can be sent back to Nauru at any point, and their parents are often left there to ensure they go back.