Jennifer Aniston is trying to get her 'Friends' co-stars to work out with her.

The 55-year-old actress - who shot to fame alongside Courteney Cox, Lisa Kudrow, Matt LeBlanc, David Schwimmer, and the late Matthew Perry in the classic 1990s sitcom - recently discovered Pvolve and is trying to get her female co-stars on board with her new regime that combines low-impact functional fitness with resistance-based equipment.

She told 'Entertainment Tonight': "It's like I found a precious stone of some sort. It's just changed my whole outlook on working out. It's something I look forward to. I'm still trying to get Courteney to take a class with me, but I'm working on her. Lisa's working so often [that] I can barely get her in Los Angeles."

But the 'Morning Show' star insisted that her new exercise regime is not a "fad" and claimed that it goes back to the age-old principle of "calories in and calories out".

She said: "Fads are what they are - they're just fads. They come and they go, and it's not very science-based or backed by much. When I was in my 20s, was there a grapefruit diet for a second there? Sure. I remember doing that. I also remember doing Nutrisystem... Things like that just aren't sustainable.

"Calories in, calories out. You put good, healthy vegetables, organic foods in your body, your body is gonna thrive on it. Put crap in your body, and your body's gonna show that.

"Your body is just a reflection of everything that you do. It's about maintaining a balance.

"Eighty percent straight as an arrow, doing all that we're supposed to do, and then give yourself 20 percent of fun.

"That's like, let's go out with the girls and get Mexican food, margaritas. Let’s have a pizza party. Let’s barbeque burgers and fries, hot dogs, by the pool. It's indulging and enjoying yourself and maybe saying, 'I'm not gonna work out today."