The famous Jenny from the block was as wracked with nerves before heading back to work on her new movie - because she feared she had forgotten how to act during her maternity break.The actress/singer gave birth to twins Max and Emme last year, her first children with husband Marc Anthony, and put her career on hold to stay at home to nurse her babies.

The star has now returned to work, filming "The Back-Up Plan," but admits she was terrified about stepping on to the set.

She tells Entertainment Tonight, "The few days before I got really nervous I was like, what if I forgot how to act?"

She adds, "I bring the babies to work with me. I love it. Honestly, one of the best days of my life was the first day back working on this film. I wanted to do this film really badly and bringing my babies with me that first morning, I was like, 'Oh my God, they're with me, I'm making a movie, they're here!' It's great having kids on set. It's the best.