Paula Patton has revealed that she felt depressed when she couldn't lose weight after giving birth to son Julian.

The actress - who is married to Soul crooner Robin Thicke - gave birth to Julian Fuego in 2010 and like most expectant mothers, she put on weight throughout her pregnancy.

However, Paula got the role of Jane Carter in Mission Impossible: Ghost Protocol but began to panic when she realised she had to get in shape for the role.

"It was really... most grueling and one of the hardest things I've done. I worked out for two and half hours, six days a week for a couple of months. It was so hard!" Paula told People magazine.

"I would never cry in front of the boys, but inside I was hurting and a little depressed. You have to get past that moment of self-doubt. After a month, the wall came down and the training felt doable. It still wasn't easy, but doable and that felt really empowering."

While she may have battled with her weight issues after the birth, Paula says that she loves nothing more than being a mother. 

"Becoming a mother is the best thing that's happened to me. [Julian]'s at the age where he's talking. He's not doing soliloquies, but he's saying 'Mama', 'Dada', 'car' and 'dog'. His vocabulary is growing every day. He makes me so happy."

Paula Patton and Robin Thicke look smitten at 'Mission: Impossible - Ghost Protocol' premiere...