Linda Ronstadt made the painful announcement last month that she was battling Parkinson's disease, and now the singer is providing more details about her struggle with the debilitating illness.

Ronstadt tells ABC News that she knew she was losing her decades-long career when singing became like the “elevator [that] would go to the wrong floor all the time.”

The 67-year-old adds that she believes she had Parkinson's for a long time before she was diagnosed. “It was hard to comb my hair," she recalls. "It was hard to brush my teeth. It was hard to wash my hair. Hard to get my hands up over my head.”

The multiple Grammy winner first revealed her diagnosis to AARP magazine. “I couldn’t sing, and I couldn’t figure out why," she explains. "I knew it was mechanical. I knew it had to do with the muscles, but I thought it might have also had something to do with the tick disease that I had. And it didn’t occur to me to go to a neurologist. I think I’ve had it for seven or eight years already, because of the symptoms that I’ve had. Then I had a shoulder operation, so I thought that’s why my hands were trembling.”

Ronstadt's memoir, 'Simple Dreams -- A Musical Memoir' was released Tuesday (Sept. 17), but does not mention her illness, as she was diagnosed after the completion of the book.