“I didn't always love my legs, but as I've grown, I've learned to love and celebrate myself, just as I am,” she wrote. “I began to realize that my legs are STRONG and they carry me every. single. day.”
In the pic, Duff is lying on a bed wearing a T-shirt and Aerie undies, kicking her bare legs up in the air.
“Our bodies are amazing and something to be grateful for,” she continued. “I'm ME and that's really enough! Thanks for helping to spread the self love message @Aerie! Make sure to share your own message about why U love U for U Day! #AerieREAL #AeriePartner.”
The actress has always been serious about taking care of her body and staying in shape. In November she split from her personal trainer boyfriend, Jason Walsh, but in her recent cover story for Cosmopolitan, Duff revealed that she took steps to keep focused on fitness during their romance.