Jessica Biel shared the well-kept secret to her incredibly toned back and arms in a social media video that dove into her workout routine, led by her personal trainer, Ben Bruno, who has worked with everyone from Kate Upton to Naomi Campbell.

The expert took to Instagram to run through Jessica's intense workout, which prepared her for Prime Video's thriller The Better Sister , the series she starred in alongside Elizabeth Banks.

© Prime Video Fans had been asking Jessica for her workout routine for months

"People have been asking about the Jessica Biel back and arms workout, and for good reason, but the truth is while she definitely does plenty of work on her back and arms, her workouts aren't split up into back day, arm day, and so on," he began, over a clip from the TV ser

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