The actress played attorney Alicia Florrick on the drama series from 2009 to 2016, and when the show ended, she struggled to say goodbye to her alter ego.
"Right after my last day on 'The Good Wife' - I'd done 156 episodes for seven years - I got home and I felt funny," she told "Live with Kelly and Ryan", "and I woke up at three in the morning and I had the chickenpox."
The star, whose new memoir, "Sunshine Girl: An Unexpected Life", hits stores on Tuesday, admitted the condition had some positive side effects.
"For three weeks I was out [sick]," she explained. "I was in bed. I had never stayed home... ever. I was always running, running, running, and if I wasn't working, I was taking care of the kid. My husband and I don't have a television in the bedroom - happy marriage, so there was no TV to watch while I was trying to scratch my eyes out."
"So I started to write and I started to write about trying to shed what I'd been doing for seven years, which was always thinking like Alicia... 'How would she react in this situation? What's really truthful?' "
"It's frightening when you have nothing else but your thoughts, but it's also a great exercise. I started to think why Alicia affected me so much... and why I couldn't let go of some of the sadness I felt for her... and I thought in order to really let this moment in my life happen, where I'm forced to look at myself because I'm in bed sick..., that was the genesis of the book."
"It's frightening when you have nothing else but your thoughts, but it's also a great exercise," she added.
And as she recovered from the chickenpox and continued writing, Julianna started to feel much happier.
"In a weird way, the [chickenpox] scabs all happened and then they all come off and it's like a new skin," she concluded, noting the condition helped her bid a fond farewell to Alicia.
"I needed to shed her in order to find me again," she smiled.