When Sheila Nevins, the four-decade veteran of HBO’s documentary division, left that company in late 2017, she refused to use the word retire. The decorated executive, then 78, thought a new adventure was in store.

On Tuesday Nevins made good on her hope, coming on to run a revamped documentary division at MTV, the group of cable networks whose flagship aims programming at teens and early 20-somethings.

“Did I think I would be back? Yes, I did. I just didn’t know if anyone would want me at this age,” the frequently candid Nevins said in a joint interview Tuesday morning with MTV president Chris McCarthy.

As for the suggestion she might have to segue into a less stressful role than the full-time running of a relaunched cable-television division, Nevins said, “I have eternity for resting. Why would I rest? Who wants to lie flat?”

MTV announced the hire with news Nevins will launch MTV Documentary Films, an expansion of sorts of its News and Docs unit that can “shepherd a new generation of documentary filmmakers exploring issues that impact youth.”

Both Nevins and McCarthy offered few details on the number or type of projects, nor where they would live. (McCarthy did emphasize the import of digital platforms, which MTV has been seeking to ramp up with a fresh slate of originals.) Nevins said there will be a mix of features and “specials,” stopping short of calling them docuseries.

But it was clear this marked a new era for a network that has long skirted the line between reality and serious nonfiction with shows such as “True Life” — the series that followed the challenges, jobs and experiences of ordinary people for nearly 20 years — as well as fizzier fare like “The Hills.”

“Sheila helped create the category so many of us grew up on,” McCarthy said. “We’re going to strive to tell stories you never knew you needed but to hear but then are so happy you did.”

At HBO, Nevins’ movies and series garnered 28 Oscars. She also has personally won 34 primetime Emmys, believed to be a record. The gay-rights examination “The Case Against 8,” the Edward Snowden-centric “Citizenfour” and the Scientology investigation “Going Clear” are among a few of the recent films produced during her tenure.

Nevins also has earned a reputation for a colorful and blunt style, which has endeared her to reporters, if not necessarily at the moment they’re on the receiving end of the colorful bluntness. Two years ago she published a book, “You Don’t Look Your Age ... And Other Fairy Tales” about her experiences as an older woman in a business dominated by men and younger women.

The hire not only marks a new turn for one of the film business’ most free-speaking executives but a sign of the strange times for cable television.

For years HBO was on the programming cutting edge for older demographics while MTV was carrying that mantle for younger viewers.

But as digital media scrambles audiences and forces a business-model rethink, HBO now has one of the most talked-about hits among young people with “Game of Thrones.” And as of Tuesday, MTV has the pre-eminent architect of award-decorated documentaries.

The move also speaks to the growing market for documentary programming, particularly docuseries. That happened in part because of shows like “The Jinx,” which was produced at HBO’s documentary division on Nevins’ watch.

Nevins said she had a one-year non-compete as she finished up HBO projects. During that time, an MTV executive who had worked with her on “Citizenfour” while at a previous job introduced her to McCarthy, who has engineered a ratings comeback at the cable network. That non-compete expired recently, and the two hatched their plan.

“When someone like Sheila becomes available, you light yourself on fire to try to get her,” McCarthy said.

Nevins said she thought MTV was the perfect role. “There’s no job quite like this because there’s no audience quite like this,” she said.

Both Nevins’ former and current company have been going through significant change. HBO is part of a larger overhaul at WarnerMedia under new owner AT&T; the company’s longtime chief executive, Richard Plepler, left in February as the company hired former NBC executive Robert Greenblatt to a new oversight position.

MTV has been part of a Viacom that remains the subject of acquisition and merger rumors. The network itself, though, is going through a stellar run. Thanks to shows such as “Jersey Shore Family Vacation,” it was one of the few on basic cable in 2018 to post double-digit gains in nearly every demographic and is now the most-watched by viewers under the age of 35. That has freed up the network to think about programming for alternate platforms, McCarthy said.

Meanwhile, a larger beefing up has been happening among media companies in the documentary space, as new entrants look to compete with Netflix, which itself disrupted longstanding powerhouses like HBO and A&E.

A&E’s longtime documentary czar Molly Thompson last month was hired by Apple to lead its nascent efforts. And one of Nevins’ former acolytes at HBO, Sara Bernstein, in September was brought on as executive vice president at Imagine Entertainment, Ron Howard and Brian Grazer’s fresh foray into the space.

Nevins’ background with edgier programming at HBO — she oversaw programming such as “Taxicab Confessions” and “Real Sex” — could fit in at MTV.

Still, the question remained: Was this MTV becoming more serious or an HBO veteran becoming more hip?

Perhaps both, Nevins suggested.

“What we’re going to try to do is shock young people into looking at the real world,” she said. “And I’m ready to give a hot young audience a special that doesn’t feel tedious.”