The singer pays tribute to his grandfather by fulfilling his final wish -- to provide his caretaker with a place to live with her family -- on Monday's episode of the HGTV series.
Having that opportunity to give back was "huge" for Bublé, who also couldn't wait to reunite with Drew and Jonathan Scott. The brothers grew up in the same neighborhood as Bublé, whose sister is still "really close" with the reality stars. However, all that excitement led Bublé to push himself a little further than his body was comfortable with during demolition day.
"I'm in much better shape than I was in that time. Much better!" Bublé confessed in an exclusive interview with ET's Kevin Frazier. "My wife’s been kicking my butt while we’re at home doing CrossFit."
On Celebrity IOU, Bublé admitted he wanted to show "how tough I was" compared to the Property Brothers. He picked up a sledgehammer, and "I was like boom!"
"I don't know what I did," Bublé said. "It was so bad that I went and got an MRI after."
"With what I went through with my son, I'm a hypochondriac... I thought, 'Oh my god, oh my god, I'm dying,' because there was literally like, a bump," he continued. "It turns out that I'm just out of shape and I'm a wimp and the sledgehammer was too much for me -- but I got in there. I refused to not be in there with them."
Noah is doing "good," Bublé happily reported. He's also developing some opinions as the singer and his wife, Luisana Lopilato, tackle homeschooling with Noah and his siblings, 4-year-old Elias and 1-year-old Vida.
"He said, 'Papi, I miss my class,' and I said, 'You do? That's really lovely, Noah.' And then he stopped and he said, 'No, no, no -- I'm not allowed to bring my toys. They tell me when I'm allowed to eat lunch. No, you know what? No, I don't miss it, I’m better like this,'" Bublé recalled.
In between parenting and encouraging fans to stay safe on his livestreams, Bublé has also found the time to make new music. His new song, "Gotta Be Patient," with Barenaked Ladies and Sofia Reyes, was created to benefit frontline workers amid the coronavirus pandemic.
"I said, 'What if I take this and put it out and we just raise as much money as we can?'" Bublé recalled.
The GRAMMY winner took a step away from music while his son was battling cancer, telling ET he's "been to hell" with that experience. Now that his family is OK, Bublé feels "obligated" to help others in any way he can.
"It's brought me a lot of joy to be connected like that, to bring those people one-billionth of the joy that they've brought me and my family," he shared.