London: R&B star Rihanna says, she had trouble in adapting to her new role as an actress on her upcoming blockbuster "Battleship". The movie centers on a fleet of naval ships fighting aliens who invade Earth to take its natural resources for their own benefit.

The 24-year-old singer said her military training for the role left her wondering why she had left the safety of her music career, Showbiz spy reported.

"We worked with real military officers who were yelling at me, breaking me down, and making me do pushups”.

"They didn't care about Rihanna, to them I was just a recruit”.

 At that point I thought 'Is this necessary? Really, Do you have to yell at me or can you just teach me how to stand to attention?’ she said.