According to Jennifer Aniston, it only gets better with age.
"I've had more fun post-40 than I can remember," Jennifer says. "From a work point of view, a physical point of view, a psychotherapeutic point of view."
And clearly, it shows -- the beloved Friends star stuns in a backless white Balmain jumpsuit on the cover, and sizzles in a low-cut black halter in another gorgeous photo from the shoot.
Jennifer gives credit to her famous girlfriends like Chelsea Handler and Courteney Cox for her current state of happiness ("I'm a pretty good judge of character, shall I say") but also to the 43-year-old Theroux.
Aniston reveals she actually took a break from dating before entering into a relationship with The Leftovers star in May 2011.
"It really helped me get to a place where I was more comfortable with myself, truly ready for love and for a partner," she explains. "It was extremely important to my growth as a woman. But if you take the law of attraction, if you only love yourself 70 percent, that's what's going to come back to you. So you fill up that 30 percent, then all of a sudden there's this pure, good love standing right in front of you. Then you realize, 'Oh, this can be easy! It doesn't have to be so hard.'"
Jennifer and Justin got engaged in August 2012, and despite now dating for more than three years, she says the two never get bored with one another.
... And she actually has his "pretty eyes" to thank.
"It's almost impossible to get bored with one another. We've tried so hard!" she gushes. "And even that's interesting because his eyes are so pretty, but we can entertain ourselves and talk about endless things, which is pretty great."
Clearly, Jennifer is still very much enamored with her man.
"Not only is he a great actor but he's one of the best comedy writers out there," she says. "And he directs and paints murals. And I just think it's so attractive to be that good at so many things and to have no ego. He's one of the most humble, decent human beings."
Harper's Bazaar's December/January issue hits newsstands Nov. 25.
ET actually caught up with the two attractive love birds at the 6th Annual Governors Awards this past weekend.
Check out their stunning red carpet appearance in the video below!