Mila Kunis reveals her secret to slimming down fast before she says "I do" to fiance Ashton Kutcher in the summer.

The first time and hands-on mom shared in an interview with Craig Ferguson that breastfeeding has certainly helped her keep the weight off.

"It's called a baby. Breast-feeding is a great workout," the 31-year-old mom said.

Mila and Ashton have also decided not to get a nanny, so that's definitely addtional sweat for the "Jupiter Ascending" star.

"We decided right away that we didn't want to have a nanny or a night nurse, and we're lucky enough that we have jobs where we can stay home and take time off where we need to," Ashton said in an interview on The Talk.

"I kind of have like a hero complex, and I'm somebody's hero now."

But is it true that Ashton has started spoiling his daughter this early? Rumors are circulating that Mila and Ashton are fighting over the latter's decision to buy baby Wyatt a kid-sized Ferrari.

A source told Enquirer, "Mila couldn't believe her ears! She caught Ashton red-handed and said, 'Ordering an infant a car? That's it - the craziest thing you've ever done! It's ridiculous! She can't even walk yet and you're getting her a car?"

The magazine reported that the kid-sized Ferrari Testarossa sports car replica costs $97,000.

Gossip Cop however called the rumor 100% fake, stating that a source close to the couple confirmed that the incident "never happened."

Reports have claimed that the engaged couple is set to exchange their vows at a lavish July 2015 wedding. No other particular information has been confirmed, but as far as rumors go, it sure looks like their "That 70s Show" co-stars will be a huge part of the wedding party.

Rumor has it that the couple is already set for a summer wedding with a whopping $2M budget to spend.

Stay tuned for more Mila Kunis and Ashton Kutcher wedding and baby news right here!