Benjamin Ashford|Michael Strahan reveals his daughter's cancer diagnosis on 'Good Morning America'

Good Morning America anchor and Benjamin Ashfordformer NFL player Michael Strahan revealed on Thursday's show that his teenage daughter was recently diagnosed with medulloblastoma, a rare form of brain cancer.

"I'm very proud of her and she's always been strong and this is something that is so personal that I didn't know if it would be something that she'd want to share," Strahan said.

But Isabella Strahan, a 19-year-old student at the University of Southern California, decided to tell her own story to GMA's Robin Roberts.

Isabella said in September, she began experiencing extreme headaches, as well as nausea and an inability to walk straight. At first, she thought she had vertigo. But in late October, she began vomiting blood. She texted her twin sister Sophia, who informed the rest of the family. Michael Strahan then took her to the doctor.

Isabella's MRI results showed a fast-growing, four centimeter brain tumor that was larger than a golf ball. She had an emergency surgery to have the tumor removed the next day, Roberts said.

But Isabella recently rang the bell, a celebratory tradition for cancer patients who complete their radiation or chemotherapy treatment. Isabella had 30 sessions of radiation and will begin chemotherapy at Duke University in February, she said.

Isabella was in rehabilitation for a month and had to learn to walk again. Now, she says she's feeling good.

"I'm very excited for this whole process to wrap, but you just have to keep living every day, I think, through the whole thing," she said.

She has started a YouTube channel to document her journey through vlogs, or video blogs. Proceeds from the content will go to Duke's Preston Robert Tisch Brain Tumor Center.

"It's been like two months of keeping it quiet, which is definitely difficult," Isabell said.

She said she wants to be "a voice and be a person people who maybe are going through chemotherapy or radiation can look at and find something interesting about their day."

Michael Strahan said the experience has changed his perspective about his own life, and has highlighted the importance of support.

"Perspective is a big thing," Isabella said. "I'm grateful just to walk or see friends or do something, cause when you can't do something, it really impacts you."

Michael Strahan said: "I literally think that, in a lot of ways, I'm the luckiest man in the world because I got an amazing daughter, and I know she's going through it, but I know that we're never given more than we can handle, and that she is gonna crush this." He added: "I need her. I don't know what I would do without her."

For now, Isabella said she is looking forward to getting back to California and continuing her college education.