The actress, 24, who welcomed son Luca Cruz on March 20, was spotted Sunday doing a little shopping at the The Pump Station & Nurtury in Hollywood.
Duff went with a sporty look with her outfit Sunday, perhaps not surprising, given that she's already hitting the gym post-baby.
"20 minutes on the elliptical seems like an eternity!!!" she Tweeted on Saturday.
On Monday afternoon, Duff shared our first glimpse at her baby boy, Tweeting a photo of his toes.
"My favorite little feet," she writes.
Courtesy Hilary Duff