The former 'Friends' star is determined to make her union with the 41-year-old actor work so before they tie the knot, she got them to have an intense three-day therapy session in Santa Monica.
A source said: ''Jennifer and Justin are super excited about their big day, but she thought it would be a good idea to start married life rid of any problems. Justin seems to be as much a believer in the therapy as Jennifer is. On arrival, they had to hand over their mobile phones and undertake counselling, couple massages and screaming therapy - where you howl your feelings out at the top of your voice.''
Jennifer, 43, also had to acknowledge the end of marriage to first husband Brad Pitt - with whom she split with in 2005 - in order to move on and make this relationship a success.
The source added to Britain's Grazia magazine: ''It was pretty tough going and they had to address all of their deepest fears and worries.''
Jennifer - who has been dating Justin for around two years - has previously spoken about having the therapy say she found it very rewarding.
She said: ''It's true that I spent some time regularly taking part in sessions with a psychiatrist. I find it very normal to lie on a couch every once in a while and to let your head be straightened out and your heart.''