CHICAGO (CBS) — Three months after surgery for a brain tumor forced her out of the race for mayor, Chicago Teachers Union President Karen Lewis spoke publicly for the first time about her disappointment that she won’t be taking on Mayor Rahm Emanuel next month.

Lewis talked politics, her health, and spirituality at a Martin Luther King Day event in the West Pullman neighborhood on Tuesday, her first public appearance since her cancer surgery in October.

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She said she has good days and not-so-good days, but she doesn’t really have bad days.

“Cancer treatment is no fun. It’s no picnic, and anyone that’s been through it knows that. I am way more spiritual about things than I used to be,” she said. “People come and tell me all the time that they’re praying for me, and you can’t help but feel better and buoyed by that.”

Lewis said she’s frustrated at not being in the race for mayor.

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“I really wanted to do this. I mean, it was something that I thought about, that I had worked it out with my family,” she said. “Yeah, it’s very disappointing.”

She said she was shocked and disappointed that medical troubles sidelined her.

“I had no symptoms. I didn’t know I was ill, so to all of a sudden going from being what you think is fine to being very ill, yeah it’s really disappointing,” she said.

The feisty teachers union leader has endorsed Cook County Commissioner Jesus “Chuy” Garcia for mayor, and said he’s making progress in his bid to unseat Emanuel.

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She said the mayor should stop running silly commercials, and save his campaign cash for a runoff election, because she predicted he won’t win a majority of the vote next month.