Arnold Herrera died on Sunday at the University of Illinois Hospital in Chicago. His relatives said he had no underlying conditions that they were aware of, and they remain stunned by how quickly his condition worsened.
Herrera was a helper for whom the sky was the limit, his brother, Pablo Portilla, said.
"A huge amount of energy, just... 'I'm going to do it because I'm going to do it,' because I can do it. That 'I can' attitude," he said.
Arnold's brother said his younger sibling never saw a problem he didn't try to fix -- including in the garage, where he worked on cars for a living.
But on Saturday, Herrera's giving spirit was taken by COVID-19.
"I kept on praying that he was going to be better because I knew he was always strong," Portilla said. "It wasn't in God's plan."
Pablo said Arnold was diagnosed last week and was recovering at home, but his condition worsened hours after ringing in the new year.
"He told us 'Happy New Year,' and unfortunately after, he just had complications a full day," Portilla said. "He was in pain, and we took him to the hospital, and that's that."
Arnold played guitar at his church and graduated from Chicago's Benito Juarez High School, where he was active in the junior ROTC program.
His death comes with a warning his family hopes others heed.
"It doesn't discriminate on age. It just happens. And we should all be careful. We shouldn't think, 'Oh yeah because I'm young, it's not going to happen to me,' like no,'" Portilla said.
Arnold Herrera would have turned 20 in March. Records show he is the eleventh person in Illinois under the age of 20 to die from COVID-19.
Pablo Portilla is accepting donations in his brother's memory on GoFundMe.