The former actor, 54, has confirmed he stepped away from Hollywood life and moved to Central America, where he has been writing a nine-book fantasy series.
Lewis, best known for playing Smith Jerrod in Sex and the City, said he spent his time surfing, learning Spanish and writing before resurfacing on social media a week ago.
In the post, he revealed he has been quietly building a fantasy book empire in Costa Rica.
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In an interview with The Hollywood Reporter, he revealed his new routine revolves around early starts, beach walks and long writing sessions.
“I do my thing and walk the beach or run the beach if the surf isn’t good yet and then have my coffee and settle in and get to the desk and have a session,” he said.
The actor added that he often wakes as early as 4am to write, aiming to produce between 1,000 and 2,000 words a day, as reported by Need To Know.
Lewis said the books are all set in the same universe across different eras, with the series described as “epic fantasy”.
He revealed he is releasing the seventh book first, explaining: “I chose to start at the end.”
The star also said his return to Instagram was encouraged by his representatives, but insisted he did not want to fall into “performative posting”.
“I very much like to try and create a community and not just be in the broadcast of, ‘Hey, check me out. Aren’t I awesome?’” he said.
Lewis admitted he is still trying to build an audience for his writing, and said he “put a lot of thought” into his first post back.
On 21 May, he posted a video of himself walking along a beach, telling fans: “After three years, it was time.”
He explained he had stepped away from public life because he was focused on creative work that “doesn’t leave room for much else”.
Lewis first rose to fame playing Samantha Jones’ younger boyfriend Smith Jerrod in the hit HBO series Sex and the City, appearing from 2003 to 2004.
He later returned for the 2008 film and its 2010 sequel.
His last acting role came in 2018 before stepping away from the screen.