Yoga fan Jennifer Aniston may not have kicked her smoking habit but that hasn't stopped her from keeping in shape, according to a new report.

The actress - whose unusual combination of cigarettes and cardio reportedly keep the actress looking slim and toned for red carpet events - manages to juggle her unhealthy habit with a much healthier one.

"The body adapts to things, just like it adapts to good diet and exercise," personal trainer Joy DiPalma tells E News!.

And it seems that Jen's keep fit regime could be the solution she needs for cutting down on her vice.

"The more cardio you do, the more you get lung capacity you get, the more your body rejects those kinds of toxic chemicals," says Bravo TV's Workout guru Jackie Warner.

She adds, "It doesn't want cigarettes; they taste dirty to you. You get headaches.

"It's really common for someone who starts an intensive program to go down from a pack a day to a half-pack a day."

It seems Jen is still waiting for this side effect to kick in...

See Jen still fabulous at 40 below