(CBS) A music writer once wrote that "when the dust settles, Joni Mitchell may stand as the most important and influential female recording artist of the late 20th century."

To that Mitchell says: "Only the late 20th century?"

She's kidding, of course, but Mitchell has had a career few artists can imagine, and has an influence that goes far beyond her folk singer roots.

She was born Roberta Joan Anderson in 1943, to an Alberta, Canada grocer and a schoolteacher. As a young girl, she was happiest outdoors, but much of her early life was marred by illness. She said she would have been an athlete had she not contracted polio, scarlet fever and severe chicken pox.

"I was shipped to another city," Mitchell tells Early Show news anchor Russ Mitchell. "So I was kind of battling it on my own. And I was in a room with a 6-year-old boy who was very depressed. And so I would sing. That's when I started singing. And he'd tell me to shut up. So I had a heckler for my first audience."

The young Mitchell soon discovered that she could make singing pay. Unable to afford a guitar, she bought a baritone ukulele for $36 and taught herself to play.

But before music there was another first love.

She always thought she would be a painter and went to art school.

"I got a gig at the freshman coffee house, which, you know, I had to pay my own way to art school. I had to back it up with rent," she said. "So I had no money for movies or bowling, which I liked also. Or cigarettes, which I've smoked since I was 9."

She began singing at the coffee house and made $15 a night, which had some significance then.

"I could bowl! I could go to movies. I could smoke, you know. I could have pizza," she said. "It gave me a little bit of income ... I was just singing folk songs then. I hadn't really put it all together. So I didn't think of myself as particularly talented. I mean, I hadn't really come up with anything particularly original."

In 1965, she was out of work and pregnant by an old college boyfriend. After the child was born, she married fellow folk singer Chuck Mitchell, who promised support for Joni and her baby, but within two years the marriage crumbled. Unemployed and penniless, she gave her baby girl up for adoption and then proceeded to pour her soul into music - music that would help define a generation.

"The first song that got fussed over was 'Both Sides Now,' which I thought was a failure," she said. "Because it was such a big meditation, you know. I've looked at these things from both sides now. I do clouds from up in the air looking down and down on the ground looking up and all the things that they do. You know, and love and live. And I was 21 when I wrote that. And I got mostly ridiculed from people, from 'What do you know about life? You're 21,' you know?"

Mitchell continued: "Well, actually at 21 I had experienced quite a lot of life. I'd had a rough childhood. I looked so innocent. But I'd had life and death struggles and things."

By the 1970s, Mitchell was an artist who seemed to have just the right voice at just the right time.

"The thing that gave me the most pain in life, psychologically, and it gave me tremendous pain psychologically, is man's disrespect for nature. It's basically been the pain of my life: the stupidity of the human animal in its relationship to the planet."

By the '90s, Mitchell was an established icon, but she was getting fed up with the music business. And by 2002, she'd all but dropped out, which meant more time for painting.

At an exhibition in New York City last month, she showed art she'd created by snapping photos of the often violent images that appeared on her home TV.

Earlier this year, the music began to well up inside her once again, even though she said she would never write songs that make social commentary again.

Her new album, "Shine," debuted last month, and after a long absence Mitchell returned to the stage in Los Angeles last weekend for a Thelonious Monk Institute tribute to her friend Herbie Hancock, who called her a great jazz singer. But Mitchell doesn't like to be labeled. She doesn't really like to perform, either.

"But I really have a desire to do ballets," she said. "I love that concept."

And yet again, her concept has become reality: "The Fiddle and the Drum" is a collaboration with the Alberta Ballet, with the dancers moving as the world has done for more than 40 years, to the rhythms of Joni Mitchell.