The singer and actress told OK! magazine that her youthful looks were down to "happiness."
The 39-year-old was speaking at a dinner to celebrate the launch of Top Shop in New York.
But it isn't smiles alone that keep her young. The actress and singer said sleep was also important.
How much shut-eye J-Lo gets is open to question though as the star has year-old twins to occupy her.
"They're walking, they're talking, babbling a lot," she told reporters.