Jeff Bezos refused to take elevators in Amazon's old office and ran up 14 flights of stairs every day without breaking a sweat, his former assistant said

• Jeff Bezos refused to take elevators and ran up 14 flights of stairs every day, a former assistant told CNBC.
• Jeff Bezos was like a "puppy" who "never tired," Ann Hiatt, who worked for Bezos in the early 2000s, said.
• Bezos stepped down as Amazon's CEO after 27 years on Monday, handing over to Andy Jassy.

Jeff Bezos would refuse to take elevators in Amazon's old office building, choosing instead to run up 14 flights of stairs every day to the company's floor, his former assistant told CNBC.

Ann Hiatt, who worked as Bezos' executive assistant from 2002 to 2005, claimed Bezos never even broke a sweat running up and down the stairs.

"He's like a puppy. He would do laps and he was never tired," Hiatt told CNBC. "That's Jeff. He couldn't be held back."

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Hiatt worked with Bezos in the 16-story Pacific Medical Center tower in Seattle, a 1930s-era former military hospital that Amazon occupied from 1999 to 2011 - Bezos was in his mid-30s at the start of that time, and his mid-40s at the end. In 2011, Amazon moved to a sprawling campus in South Lake Union, Seattle.

Bezos stepped down as Amazon CEO after 27 years on Monday, after first announcing his departure in a letter to employees in February. He has handed over to Andy Jassy, formerly chief executive of Amazon Web Services.

Hiatt previously told the New York Times that Jassy was Bezos' "brain double" in the early 2000s, and would shadow him in meetings and help challenge his thinking.

Since Bezos founded the company 1994, Amazon has grown into a$1.8 trillion dollar business, employed 1.3 million people, and made Bezos the richest man in the world, with a $203 billion net worth, according to Bloomberg's Billionaires Index.

Jassy will now have to deal with criticism from lawmakers and employees over tough working conditions. Some Amazon delivery drivers previously told Insider that they had to urinate in bottles because their grueling schedules did not allow them enough time to go to the bathroom.

Bezos said that the company needed "to do a better job" for its workers in his 2020 letter to shareholders, after the National Labor Relations Board announced in April that a push by some Alabama employees to form a union had failed.