Cover Story: Jen's Wedding of the Year!

In the coming months, Jennifer Aniston will be celebrating two major milestones in her life: turning 40, and marrying the new love of her life, John Mayer.

"She's at an age where she is thinking with her head not just her heart," a source close to the actress tells OK!, adding that the event will take place this fall. "No way would she still be with anyone if marriage wasn't a real option."

When Jen married Brad Pitt eight years ago, they spent $1 million on the ceremony, which featured a gospel choir, four bands, fireworks and an estimated 50,000 flowers!

But this time around, Jen wants something entirely different. "She doesn't want anything elaborate or showy," one friend tells OK!.

With best friend Courteney Cox as her matron of honor and godchild Coco Arquette as her flower girl, Jen will have all the attendants she needs or wants.

With both of them sharing the same laid-back and down-to-earth lifestyle, friends say Jen and John, 30, are made for each other.

"They are just a perfect match," says a friend. "And everything about that will come through in this beautiful wedding."

For the complete story on Jen's wedding of the year, pick up the new OK!--on newsstands everywhere on Thursday!