If the red carpet at Sunday's Billboard Music Awards was any indication, then belly-baring cutouts are the celebrity fashion trend of the moment. Taylor Swift and Empire star Taraji P. Henson both rocked sleek side cutouts that gave us a peek at their flat stomachs; Rita Ora showed off her belly button (and much more) in a revealing white gown; and although Jennifer Lopez may be known for her bodacious booty, her sparkly silver-and-white number put her rock-hard abs front and center. Hello, #fitspiration!

Feeling motivated to sculpt your own stomach? Lucky for you, the trainer who helped J. Lo develop her killer abs is Tracy Anderson, Health's contributing fitness editor. In this workout, she shows you how to do four powerful variations on the plank that are designed to tighten and tone your middle. Do these moves six times a week, paired with 30 minutes of cardio.

RELATED: 11 Exercises That Build Muscle Without Bulk