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."