"I would tell my mom not to talk to me when it was on," Ballas confesses.
Now, Ballas is again giving Hart all his attention by teaching her how to dance.
The pair will compete together on the ninth season of "Dancing with the Stars" premiering at 8 p.m. EDT Sept. 21 on ABC.
They're on their eighth day of rehearsals and Hart, who also starred in the TV series "Sabrina the Teenage Witch," is ready to start doing lifts and stunts.
"She's doing pretty well so far," says Ballas, 23. "She has a tendency to kind of want to do all the hard stuff now. We've got to build up to it. We're only on day eight. We have three more weeks to go."
"See, I kind of look at it like, 'We have three more weeks to go!'" admits Hart, 33.
She's got a good teacher. Ballas took his season eight partner, Olympian Shawn Johnson, to first place. He also won the sixth season of the show with partner Kristi Yamaguchi.
Take a look back at the previous eight seasons - the winners, losers and highlights from the shows.
But on the upcoming season of "Dancing With the Stars," Ballas won't just dance. He'll sing, too. He and fellow "Dancing" cast member Derek Hough have a band and will perform music on the fifth episode.
At the end of the year, they'll release their second album.
Hart will compete against other celebrities like Donny Osmond, Macy Gray and Kathy Ireland for the coveted disco ball trophy, but Ballas is trying not to speculate on who will be real competition.
"There's always a bit of gossip. There's always 'Oh, I heard this one's good' but you never know until you see them dance," Ballas says.