IT WAS A MOMENT when memories were made, beautifully, poignantly, publicly. Brian O’Donovan, celebrating the 20thyear of his annual live show “A Christmas Celtic Sojourn,” stood onstage at Boston’s Cutler Majestic Theater with his wife and two of his daughters, along with the rest of the cast. As the audience joined in, they sang the traditional English carol, “The Wassail Song,” which concludes, “God bless you and send you a Happy New Year.”

Fans who have followed O’Donovan’s two decades as the face of Celtic music in Boston know the O’Donovan family may not have a happy new year. Brian O’Donovan has been diagnosed with glioblastoma, terminal brain cancer.

Facing that reality, O’Donovan said on this week’s Codcast that those moments of song with his family meant an awful lot. “The fact that they were there on stage singing Christmas songs with the audience, with everybody who was gathered on stage, I don’t take that type of thing for granted,” O’Donovan said. “I take it as a special golden moment. And it came through to me very, very poignantly.”

O’Donovan, the long-time host of GBH’s weekly show “A Celtic Sojourn,” faces his dire prognosis with optimism and grace. O’Donovan says he has no choice. “I can’t go back and take door B,” he said.

When he talks publicly about his diagnosis, O’Donovan focuses on the good. “I’m a people person, and even under such bleak circumstances and prognosis, there are opportunities to see kindness coming through, and I have seen that,” he said. “I’m a big fan of poetry, and I see poetry almost like prayer these days. And people send me poems and send me prayers ‘I’m Jewish and I’m praying for you. I’m Muslim and I’m praying for you. I have no faith-based beliefs and I’m praying for you.’ And I take those prayers as any sort of positive vibes.”

O’Donovan said on the advice of his medical team, he is taking life one day at a time. “I will continue in my life until I can’t,” he said.

Most of the Codcast focused on O’Donovan’s passion: Celtic music, a folk style that originated in the areas around Ireland, Scotland, and Wales.

O’Donovan, a native of Clonakilty West Cork in Ireland, was raised in a musical family, with a father and siblings who would sing as they worked or walked to school. He grew up in the 1970s, at a time when traditional Celtic music was being redefined with different instruments and harmonies.

O’Donovan has since sought out music that takes traditional Celtic music and builds upon it, incorporating artistic styles from diverse cultures. His Christmas show this year included a nod to the Jewish holiday of Hanukkah with a performance by singer-songwriter Lily Henley, who sang in Ladino, celebrating the Judeo-Spanish tradition. O’Donovan credits the famous show Riverdance for bringing Irish dance and music into modern culture – and for encouraging the mingling of dance styles, like Irish steps, American tap, and African American dance.

“I keep saying that Celtic music is a living thing,” he said. “It’s not just something to be pulled out of a dusty drawer. It lives and is vital and vibrant in the communities and also seeks to collaborate with other forms of music and has been successful in doing that.”

O’Donovan believes music has a vital role in today’s divided society. “If you talk politics, if you talk history, even if you talk literature, at times they seem to have that division built into them,” he said. “I think that music and songs and dancing seem to eliminate that and invite people in on their own recognizance. And I think that’s a golden opportunity for us to use what we know, in our access to musicians and dancers and singers, to use that access to bring people together.”

While one critique of arts organizations has been that high prices make art the province of the elite, O’Donovan is hopeful that will change with more state and federal government financial support, as policymakers increasingly recognize that arts access is a human rights issue. “In the past, the value of arts to creating community and to community-building has been undervalued. And I think that’s changing,” O’Donovan said. With the pandemic not allowing us to gather with like-minded people to enjoy the art, I don’t think anybody wants that to happen again, whether it’s to a pandemic, to a virus, or to lack of funding or lack of attention on the arts.”

As he faces his illness, O’Donovan turns to the arts for guidance. He often quotes the epitaph written on Irish poet Seamus Heaney’s grave, a line from one of Heaney’s poems: “Walk on air against your better judgment.”

“I really take that as a kind of a philosophy, almost, at this particular point, that I want to be as optimistic as I possibly can, knowing the bleakness of my situation as a reality, but also to walk on air, meaning, I think, take chances that you might have put off at other times in your life,” O’Donovan said.

“I’m saying this to all of the audience out there, do what you do and do it best and do it with a hunger and a desire for it, because you never know what’s coming down the road,” O’Donovan said. “And that’s certainly true in my case. But I’m going to walk on air. Maybe against my better judgment, but to heck with it. I’m still going to walk on air.”