AceShowbiz - Jennifer Aniston loves to climb into the boxing ring to keep fit because it's also a good way to work out all of her aggression.

The former "Friends" star is known for her slender frame, and although she likes to try out new forms of exercise, it's rare for her to keep them in rotation with her longtime love of yoga.

"I have a lot of favourite workouts. Variety is the key for me," she previously told Women's Health magazine.

However, that all changed when she stepped into the ring for the first time last year, and now she cannot get enough of the contact sport.

"Last year I discovered boxing, and I love it," she tells InStyle magazine. "I have this trainer named Leyon... It's the longest workout I've actually stayed with consistently other than yoga."

Jennifer finds the activity is as much of a workout for her mind as it is for her muscles: "There's something about the mental aspect of boxing - the drills, your brain has to work, you're not just sitting on a bike. It's amazing," she smiles.

And it's perfect for when she's holding a grudge against someone.

"Boxing is a great way to get aggression out," the actress continues. "You get a mental release of all this crap you're taking into your ears and eyes every day and have little fantasy moments imagining who you're actually punching. I'm just grateful it's not actually the person, even though there's one person (I'd like to punch). You know what I mean. It's all good."