"Jake is my hero, he really is," Grunberg, 41, tells PEOPLE about his 12-year-old son, who has epilepsy. "He doesn't let anything stop him, and to deal with everything with your head up high, that to me is a true hero."
His son has been the inspiration behind his involvement in raising awareness about the neurological disorder, which includes raising funds for pediatric epilepsy research.
As drummer for Band From TV, Grunberg – along with House's Hugh Laurie on piano, Desperate Housewives' James Denton on guitar and Cashmere Mafia's Bonnie Somerville and former Bachelor Bob Guiney on vocals – hosts concerts with proceeds benefiting charity. Past guest singers include Teri Hatcher and his Heroes costar Hayden Panettiere.
The band, whose last gig was on American Idol's Idol Gives Back show, will perform and host the Ford Flex Rally, a charity event launching Ford's new crossover SUV, in Los Angeles on June 21.
Lucky to Be His DadJake, his father says, is "doing well [though] it's tough because he's also going through puberty" and having one to two seizures a week, including one episode a few minutes before his school's talent show, where he was scheduled to do a Taekwondo routine to the Rocky theme song "Eye of the Tiger."
"I was like, Jake, don't worry about [the show], it's not a big deal," he recalls. "But he had this steel look in his eyes and said, 'I'm doing it.' If that happened to me I would go home and bury my head in the sand. He doesn't let anything stand in his way. I'm so lucky to be his dad."
As for Jake's support system, it's a family affair that includes mom Elizabeth, 41, and younger brothers Ben, 8, and Sam, 4. "In our house we say we all have epilepsy," Grunberg explains. "We're all watching out for him. We're all going through this together."
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