Folk music icon Judy Collins doesn't believe in aging, she says. Or retirement.

"Life is like rehab," she says in a telephone interview. "We're always trying to get it right, you know. Aging is a process that is revealing and demanding."

That process led singer and songwriter Collins to record about 50 albums — if all her studio albums, live albums and compilations are added together. Her interpretation of Joni Mitchell's "Both Sides Now" from her landmark 1967 album, "Wildflowers," is in the Grammy Hall of Fame. Her version of Stephen Sondheim's "Send in the Clowns" was named Song of the Year at the 1975 Grammy Awards.

Now, she and longtime friend and fellow Laurel Canyon musician Stephen Stills have a new album, "Everybody Knows," to be released Sept. 22 on Wildflower/Cleopatra Records, and the two embarked in July on a 50-city tour around the country.

"It's so much fun, it should probably be illegal," Collins says of the Stills Collins Suite Tour hitting Friday, Sept. 8, at the Britt Pavilion in Jacksonville. "I'm just having a ball. I'm the second guitar player in a rock 'n' roll band with Stephen Stills. How could that be bad?"

Stills and Collins met in 1967 and dated two years. Their careers led their visionary approaches, but their short union was transformative. He wrote “Suite: Judy Blue Eyes,” recorded on Crosby, Stills & Nash’s self-titled debut album, for her. They’ve remained friends the past 50 years, but never recorded together — or performed together — until now.

"It's a natural thing," Collins says. "We talked about it on and off for a long time, then a couple of years ago we got serious about it and started thinking about songs we might do together and trying to picture what it would be like.

"It's a total privilege. We feel so blessed to be able to do this. In a way, it's highly surprising, but then on the other hand it was inevitable. It's such fun."

"Everybody Knows" includes reworked songs from the past, such as “Who Knows Where the Time Goes,” the title track from Collins’ 1968 album, and “So Begins the Task,” from Stills’ 1972 debut with Manassas.

They also cover songs by Bob Dylan (“Girl From the North Country”), Leonard Cohen (“Everybody Knows”) and the Traveling Wilburys (“Handle With Care”). Collins contributed one new song, “River of Gold,” to the project, and Stills wrote "Judy."

"You know the story, he wrote 'Suite Judy Blue Eyes' for me, and he also wrote 'Judy' for me, which he says was the predecessor," Collins says. "He had never done it, nor had he finished it really. So we're having a lot of fun with that song."

Collins says there are no songwriting collaborations on the album, only duets.

"We're singing songs that either I wrote for him or he wrote for me," she says. "Or favorites of ours that we do together, except for our solo spots. In the show, each of us has a little solo spot. So that's fun. I do 'River of Gold' and 'Houses,' which I wrote for him on 'Judith' in 1975, a big album of mine. Stephen does 'Treetop Flyer' and one other.

"We laugh a lot. Everyone is goodnatured. It's smooth sailing. Stephen travels on his bus, the band travels on its bus, all of the equipment travels in a beautiful, shiny blue truck, and I fly," she adds with a laugh.

"We'll probably do it again after we finish this up, so that's nice. We're thinking about doing another album together. Hopefully we'll keep our minds open about touring. There's a lot of interest. A lot of people want us to come see them. We'll see where it goes."

"Everybody Knows" releases on the heels of a busy time for Collins, who released "Strangers Again" in 2015 and "Silver Skies Blue," an album of duets with Ari Hest, in 2016. "Strangers" garnered a high Billboard 200 debut, and "Skies" earned a Grammy nomination for Best Folk Album.

In 2013, the New York Times described Collins as "that ageless wild angel of pop."