"He killed the gym this morning," Stefani marveled. "It's funny because he’s so tall that like, literally no sweat suits fit him."
Levine, however, had a hard time believing his longtime co-star and friendly rival would even step foot in a gym.
"I feel like you'd be there for five minutes and he’d be like, 'I'm havin' a heart attack!'" Levine joked.
"Actually, it's because of him that I worked out this morning," Stefani explained. "I wasn’t gonna work out… He's my trainer."
The No Doubt frontwoman took to Snapchat on Tuesday to share a few pics and videos from their workout adventure, writing that the couple "Man handled the gym today."
As much as Stefani seems to love it, getting healthy appears to be taking a toll on her boyfriend.
Shelton also said Stefani doesn’t really need to work out. "I mean look at [her]. Wouldn’t you like to be born with her genetics? It’s not fair!"