The recovering starlet wore black capri leggings and a loose-fitting t-shirt for her workout session and she was reportedly dropped off at the gym by her mother.
Bynes began working on getting her old body back last week as she enrolled in the intensive seven-day Fitness Jumpstart program at Miracles Fitness Retreat in Utah which retails for $3,250 for the week.
Bynes has been spending a lot of time with her parents since she completed her rehabilitation at a Malibu treatment facility in early December. Since her release, she's been seen walking her dog, at Disneyland and grocery shopping with her parents a few times.
In addition to attending school part time and hitting the gym every now and then, the She's the Man star agreed to see a counselor twice a week for the next six months as part of a deal to settle her New York bong-tossing case.
Swim Week Miami Beach 2014 [PHOTOS]