As he closes in on completing his first 100 days in office, Donald J. Trump reflected on how his life has changed since he became president and the challenges he faces.

In an interview on Thursday with Reuters, the president offered these assessments:

On the difficulties of the job

“I loved my previous life,” Mr. Trump told Reuters. “I had so many things going. This is more work than in my previous life. I thought it would be easier.”

On a confrontation with North Korea

“There is a chance that we could end up having a major, major conflict with North Korea. Absolutely.”

On China’s role in holding off North Korea

Referring to President Xi Jinping of China, Mr. Trump said: “He certainly doesn’t want to see turmoil and death. He doesn’t want to see it. He’s a good man. He’s a very good man and I got to know him very well ...”

On North Korea Leader Kim Jong-un

“As to whether or not he’s rational, I have no opinion on it. I hope he’s rational.”

On breaking away from Nafta

“I get a call from Mexico yesterday, ‘We hear you’re going to terminate Nafta.’ I said that’s right. They said, ‘Is there any way we can do something without you – without termination?’ I said, ‘What do you want to do?’ He said, ‘Well, we’d like to negotiate.’ I said we’ll think about it. Then I get a call, and they call me, I get a call from Justin Trudeau and he said, ‘We’d like to see if we can work something out,’ and I said that’s fine. Because I’ve always — I’ve been very consistent. It’s much less disruptive if we can make a fair trade deal than if we terminate.”