Jennifer Aniston prepares for romantic getaways with squats.

According to the former 'Friends' star's yoga instructor, Mandy Ingber, Jennifer likes to ''tighten up'' before going on short breaks with her actor fiance Justin Theroux and focuses on the butt-shaping exercises to lift her posterior.

Mandy told ABC News: ''She focuses on butt exercises for sure, I'll add some squats into the yoga routine.

''For me, there's no better thing to lift your butt than squats. Pretty much, that's gonna do it... Most of us want that area a little higher.''

Unlike yo-yo dieters, Jennifer, 45, is said to be very ''consistent'' when it comes to getting into shape and knows which fatty foods to avoid to stay trim.

Mandy explained: ''Jen's a very consistent exerciser and eater.

''But when she has something she needs to focus a little more on, she just tightens it up a little bit. She won't have the extra chips.''

Meanwhile, the 'We Are The Millers' star recently revealed she was banned from undergoing plastic surgery or botox by her 43-year-old husband-to-be, saying he ''will put a gun to my head if I touch my face in any way.''

She told Yahoo! Beauty: ''I think, what I have been witness to, is seeing women trying to stay ageless with what they are doing to themselves.

''I am grateful to learn from their mistakes, because I am not injecting s**t into my face. I see them and my heart breaks. I think, 'Oh god if you only know how much older you look.' They are trying to stop the clock and all you can see is an insecure person who won't let themselves just age. I also have a fiancé who will put a gun to my head if I touch my face in any way.''