Diane Sawyer remembers which classic song Richard Simmons quoted in his final lyrics (exclusive)

Diane Sawyer revealed the last messages she and Richard Simmons exchanged before his death.

Simmons died on Saturday, July 13, at his home in Los Angeles. He was 76 years old.

The 78-year-old broadcast journalist says she and the late fitness guru had previously had “wonderful conversations.” Before his death, Simmons agreed to an interview with Sawyer, she says.

“I was truly moved by Richard’s layered insights into life and people, including himself – how we rise and how we fall,” Sawyer tells PEOPLE. “I will always remember the room full of flowers he sent me, and how each bouquet contained the same message: I trust you.”

“Richard’s last text message to me was straight from the (Carole King) song ‘You’ve Got a Friend.’ If you want to talk, just call my name and I’ll be there,” Sawyer says.

Simmons’ longtime press agent Tom Estey confirmed his death to PEOPLE on Saturday.

“The world has truly lost an angel,” Estey told PEOPLE.

Two days before his death, Simmons spoke exclusively to PEOPLE in a rare interview and revealed how he would celebrate his 76th birthday on Friday, July 12.

“But the candle will probably be on a zucchini. You know, I’m a vegetarian,” he said, adding that he would “maybe try a Pepperidge Farm Milano cookie.”

“I feel good!” Simmons said. “I’m grateful to be here and to be alive for another day. I’m going to spend my birthday doing what I do every day: helping people.”

Simmons told PEOPLE that his “parents instilled in him a need” to help others, adding, “Caring for people has always been something I care about.”

He said it was “shocking” to hear what his desperate fans were telling him. “Especially when (the people I’m talking to) are young and they feel like they’re not accepted. And they feel like they’re not loved. Then they want to take their own lives. And believe me, I’ve made calls like that.”

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Although Simmons had been out of the public eye since 2014, he remained in touch with his fans as he chose to “live a more private life,” Estey told PEOPLE in 2017, adding, “If he decides to come back, he will come back.”

Simmons plans to return to the spotlight, his brother Lenny told PEOPLE, noting that his brother was “very excited about all of his upcoming projects that he was working on.”

“I don’t want people to be sad about my brother,” Lenny said. “I want them to remember him because he brought real joy and love into people’s lives. He really cared about people. Over the course of his career, he called, wrote and emailed thousands of people to offer them help.”

“So don’t be sad. Celebrate his life,” Lenny continued.