The 52-year-old Hamilton raised more than $1 million for cancer research this month despite being on the mend for surgery on both the tumor and a later aneurysm that cost him much of the sight in his right eye.
"I tried to stay positive through all this," Hamilton told People magazine. "But in the back of my mind, I felt, 'I'm getting knocked down and I'm not sure if I can get back up.'"
Country singer Brad Paisley, a longtime friend of Hamilton, told People, "He's a hero to me in the way he handles adversity and his positive outlook on life, no matter the circumstances."
Hamilton's brain tumor was his third bout with cancer, People said Saturday.
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