You ever wondered why Priyanka Chopra calls Mary Kom` her most difficult and challenging movie ever, here`s the answer to that. In a brand new video showcasing behind-the-scenes training sessions of Priyanka during the movie, we get to see the painstaking efforts of the actress during the 3 months of her non-stop training that goes on to continue during the shoot as well.

The video captures the undying spirit of Priyanka Chopra as she pushes herself to be the best under gym trainer Samir Jaura`s guidance. She has trained hard to prepare for her role as the five time world champion and Olympic player MC Mary Kom and has been successful in achieving the brawn look due to her unending fortitude and constant need to evolve herself.

Watch Making of 'Mary Kom'