AceShowbiz - Jennifer Garner convinced film bosses to let her use her history as a TV spy to take charge of her own training regime ahead of new action movie "Peppermint".

The actress plays a mum seeking revenge on the drug cartel bosses who gunned down her husband and daughter in the hard-hitting new movie, and she admits she knew exactly what to do to get in shape for the role thanks to the years she spent playing Sydney Bristow on hit television series "Alias".

"There was a lot of training, it was very physical," Garner told Entertainment Tonight. "I was in pretty good shape going into it, and I said to them (movie bosses), 'You know, I know how to train for this movie, I can get where I need to go and I know what I need to do'. And they said, 'OK'."

Garner turned to her personal trainer and hooked up with her longtime stunt double for intense work-out sessions.

"We did a lot of dance, cardio, but we also you know did crazy weights and I did bands, and trampoline...," she beamed. "I also boxed every day, and then I trained with the stunt team.

"At first, when we started shooting, I would be back in action mode. I would just kind of fall into being Sydney Bristow," Garner said. "I walked liked her because my body had this memory of it. But Sydney was an optimistic young girl who was out to take care of things, but she had an optimism to her, whereas my character Riley North (in Peppermint), everything has been taken from (sic), and she is at the depths of the depths and is coming at it from an almost animalistic point (of view)."

And it was great to reunite with old pal Shauna Duggins: "My stunt double and I have worked together since, I think, the third or fourth episode of Alias...," she added. "She's like my sister, so (it has been good) for the two of us to get to be together every day, to train together, to go back to all of that."

Peppermint is released in America on Friday, September 07.