Through his daughter Isabella’s toughest times, after her brain tumor was removed and she was undergoing another round of chemotherapy, Michael Strahan kept looking “to find the silver lining somewhere,” he says, “some light at the end of the tunnel.”

It was early 2024 and Isabella, then 19, was battling medulloblastoma, an aggressive brain cancer. “She wasn’t eating much,” says Michael. “She was thin and tired and bald and all the things you hate to see your kid go through.” Still, he adds, “Her spirit was there. One of the things she said, probably the hardest thing I had to hear was, ‘Dad I’ll do whatever. I want to live.’”

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Michael Strahan with his twin daughters, Sophia (left) and Isabella.Victoria Will

“I knew she wouldn’t quit,” says the Good Morning America co-anchor, 53. “She was going to fight — and she did.”

After going through multiple rounds of radiation, grueling chemotherapy and several surgeries, Isabella, now 20, is cancer-free. The Strahan family shares the story of her battle in this week’s PEOPLE, ahead of an upcoming ABC special: Life Interrupted: Isabella Strahan’s Fight Against Cancer, airing Feb. 5 at 10 p.m. and the next day, Feb. 6 on Disney+ and Hulu. As Michael, a Pro Football Hall of Famer, puts it, “I always say she’s a lot stronger than I am.”

Michael Strahan and his daughter Isabella.Victoria Will

Back in the fall of 2023, when Isabella was starting her classes at the University of Southern California, she began experiencing nausea, dizziness and debilitating headaches. She confided in her twin sister, Sophia, then a freshman at Duke University. “I was the one who told our parents (Michael and former wife, Jean Muggli) first,” says Sophia, “because Isabella called and said she was throwing up blood.”

Sophia convinced Isabella to go to the ER, where she was met by her family. (“They dropped everything,” recalls Isabella). Doctors explained she had a fast-growing tumor in her cerebellum, the part of the brain that controls balance and coordination. Says Michael, “They said no need for a second opinion. We should just go in.”

Twin sisters Isabella and Sophia Strahan on July 10, 2015, in Washington, D.C.Michael Strahan/Instagram

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The next day, on Oct. 28, her 19th birthday, Isabella had brain surgery to remove the 4-centimeter tumor. According to Dr. David Ashley, a neuro-oncologist who oversaw her care at Duke Children’s Hospital in North Carolina, “It was somewhere between the size of a golf ball and a tennis ball.”

For the next eight months, Isabella was in and out of the hospital and underwent two follow-up surgeries to clean out an infection around the surgical site and replace part of her skull with a titanium mesh plate. “That was the first time I saw her cry,” recalls Michael.

Isabella Strahan in the hospital.Isabella Strahan

Her family and friends rallied around her. “My mom would sleep in the hospital with me,” recalls Isabella. Adds her mom, Jean Muggli, “Isabella’s strength and resilience was the same as it was when she was a little girl. The way she handled every day with grace was amazing.”

Isabella Strahan with her mom Jean Muggli in October 2023.Jean Strahan/Instagram

It was often one step at a time — literally — as Isabella had to relearn to eat, talk and walk, sometimes with Sophia pushing her wheelchair. “She would say to me ‘I just want to feel normal. Nothing in my life is normal,’” recalls Sophia. So that’s what Sophia tried to help her achieve. “Even though,” she adds, “Nothing she went through was a normal experience.”

Isabella Strahan and her twin sister Sophia.Victoria Will

Isabella documented those experiences in real-time in a series of YouTube vlogs to connect with other cancer survivors, especially people her age. She donated the YouTube proceeds to the Preston Robert Tisch Brain Tumor Center, where she received care at Duke University.

Now back at USC, Isabella is majoring in communications. She’ll continue to have scans every three months for the next two or three years and then every six months to a year after that.

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“Her doctors feel very confident, she’s going to be fine,” says Michael. “That’s what we’re going to hold on to, but you’re nervous every time. That will never go away but as long as the results come back positive, then we’ll live to fight another day.”

“Obviously you can’t predict what will happen and that’s a little scary,” Isabella reflects. “But I don’t think you can solely live in fear. I think I should live every day. Take every opportunity. I see the impact that can come from sharing my experience. I want to be a voice.”