"I have tried working out a couple of times with her and afterward, I can't move,” says McGraw, who sometimes joins Hill at their home gym to burn calories.
When asked about her routine, McGraw jokes, "It's like, leg warmers and Olivia Newton-John's 'Physical.'"
A high-pitched giggle from Hill interrupts McGraw, forcing him to set the record straight: "Faith says it is nothing like that." McGraw then pauses before going on, "But yeah, it's me with my headband on and leg warmers..."
For McGraw, there was a time when embarrassing Hill was no laughing matter.
The country superstar, 45, admits he was drinking and partying to an extent he felt was out of control.
"I wasn't a beer drinker. I was more a whiskey drinker. And I wouldn't just have a drink. If I was going to drink, I'd have some drinks," says McGraw.
"People were worried about me. It was to the point where I felt it was negatively affecting my relationships and getting in the way of things I wanted to accomplish in life. So I quit."