Jennifer Aniston is looking fit and fabulous on the cover of GQ Spain's July/August issue.

The 43-year-old actress, who just returned from a tropical getaway with her beau Justin Theroux, opens up about how it feels "being over the hill." Jen tells the mag, "I'll tell you when I think the 40's are great."

Aniston is currently working on two projects ... We're The Millers opposite Jason Sudeikis and Miss You Already co-starring Toni Collette.

Will we ever see Ms. Aniston in a period-type piece? She adds, "I have no desire to make a Shakespearean film. I want action!"

We have a feeling Mr. Theroux is providing plenty of that!