Luca Cruz is turning into quite the little beach baby!

In a new Twitpic captioned "Paradise", new mom Hilary Duff is all smiles as she holds up her son, 3 months, during their beach day together on Thursday.

The Lizzie Maguire alum has been soaking up the sun on her vacation in Mexico, where she is joined by hubby Mike Comrie, her sister, Haylie Duff, and her mother, Susan Duff. On Wednesday, Hilary debuted her post-baby bikini body in a black two-piece.

PHOTOS: How Hilary prepped for motherhood

Earlier this month, the 24-year-old actress and singer told Us Weekly she is determined to drop the baby weight, but in a healthy way. "I think if you ask any pregnant mom, they're like 'I want my body back,' but it takes time. It takes nine months for your body to get that way and it's putting on that weight on purpose."

PHOTOS: More cute celeb kids at the beach

"Obviously, I'm not where I want to be eventually, but I'm working hard and I'm doing everything I can to lose the weight the right way," she added. "The second I start to get down like 'what happened to my body,' I look at my beautiful baby and I've never been more appreciative for this body that I have."

This article originally appeared on Hilary Duff Poses on the Beach with Son Luca, 3 Months