Gayle King is co-host of “CBS This Morning,” which celebrates five years on the air this week.

For Gayle King, being Oprah Winfrey's best friend has its privileges — and some obligations.

One of them was alerting Winfrey, an avid reader, to what was happening on television.

“They used to call me 'Gayle King, Eyewitness News' because I'd call and say, 'Oprah, turn on the TV, O.J. is on the run,'” King recalled during a recent lunch in Manhattan. “She once said, 'There's this show “Friends,” have you heard of it? They're coming to me and asking if I want them on the show.' I was always her touchstone for what was going on in the world.”

These days Winfrey is getting her updates from King along with the 3.7 million viewers who watch her on “CBS This Morning,” which celebrates five years on the air this week.

At 62, King has reached a new pinnacle in a four-decade career by becoming a morning TV star alongside co-anchors Charlie Rose and Norah O'Donnell. She recently signed a lucrative long-term deal to remain with the program, which launched with the bold claim that “The News Is Back in the Morning.”

King recalls how some critics believed the positioning of the show as a smarter alternative to NBC's “Today” and ABC's “Good Morning America” was ambitious and perhaps a bit audacious.

“We had a lot of haters and a lot of naysayers,” she said. “We didn't know what was going to happen.”

But along with the ratings growth that “CBS This Morning” has experienced — up 45 percent since its first year — King says she knows that the program has lived up to its promise. Her friends who work for the competition tell her so.

“They'll say, 'It's so frustrating to see what you're doing compared to what we're doing,'” King said. “Friends from other networks, including executives, have all come to me at different times to say, 'I like what you guys are doing, I wish we were doing more of it.'”

Such candor is common from King. Morning TV anchors don't normally use the term “bad ass” to describe an upcoming guest, but King does. She is freewheeling when it comes to talking about her own life. She doesn't shy away from discussing her age. She posts on Instagram about her weight.

It's King's willingness to speak her mind that adds a what-will-she-say-next tension to “CBS This Morning” and has people like former “Today” co-anchor Bryant Gumbel watching.

“You watch her and you can see there is no guile,” said Gumbel, now the host of HBO's “Real Sports.” “Her edit button, like mine, doesn't work. My edit button doesn't work in an acerbic way. Her edit button doesn't work in a nice way. Sometimes she says things that make me laugh out loud. She's a good person, and she has natural curiosity and natural enthusiasm.”

People who have worked with King describe her as having a sunny personality even when the camera is not on her. (“Yellow is my favorite color,” she said, confirming the description.) She is described as a morale booster in the “CBS This Morning” studio, knowing the names of each staffer and crew member.

King says being on television has always made her happy. (“I would say I'm having the best time of my life, but I was having a great time anchoring local news.”)