"Some people can't take it. As much as they want to, they can't take it," explained Trump.
Commerce Secretary Wilbur Ross may have fallen out of favor with the president.
Trump "is committed to streamlining government for the 21st century," a White House spokesman said.
The former Montana congressman and Navy SEAL has faced plenty of questions about his air travel as secretary of the interior.
The former White House communications director's new "media venture" got slammed as being tasteless for tweeting a Holocaust poll.
Donald Trump's former communications director is amped up about his new media venture. As to exactly what it will be, he'll get back to you on that.
Top advisers to his predecessor worry Trump is waiting too long to build a team to advise him on everything from national defense to public health.
Some of Trump's cabinet choices weren't confirmed by the Senate until April.
He also named retired U.S. Army General Keith Kellogg, who had been serving as acting national security adviser, as chief of staff to the National Security Council.
Retired Lieutenant General Keith Kellogg will act as interim national security adviser.
Despite concerns about the former Exxon Mobil CEO's ties to Russia, he won a 53-42 vote.
The South Carolina governor is the fourth confirmed cabinet member.
Representative Tom Price of Georgia faces a second Senate committee on his nomination for health secretary.
Perdue served on Trump's agricultural advisory committee during his presidential campaign.
Could ethical questions doom any of the president-elect's nominations?
U.S. President-elect Donald Trump has chosen pro-Russian Rex Tillerson for secretary of state.
Meanwhile, Donald Trump has been selected as "Time" magazine's Person of the Year.
Trump's transition team doubles down on Taiwan call, terming it a "courtesy."
The new head of the Department of Health and Human Services could repeal the Affordable Care Act and restructure Medicare and Medicaid.