Planning the wedding? Jennifer Aniston and Justin Theroux sunbathe with Emily Blunt, John Krasinski and Jimmy Kimmel in Cabo

 Jennifer Aniston and Justin Theroux are busy planning their wedding.

So who better to help than a happy pair of newlyweds and another engaged couple?

The vacationing stars were joined in Cabo San Luca on Thursday by a clutch of their famous friends - British actress Emily Blunt and her husband John Krasinski and Jimmy Kimmel and his fiancée Molly McNearney.

Working out together much? Jennifer Aniston and her fiancé Justin Theroux spent Thursday tanning their impressive physiques side-by-side in the hot Mexican sun 

Where's the sparkler? However, Jennifer did not appear to be wearing her massive eight-carat engagement ring, estimated to have cost Theroux $500,000

It is safe to imagine the talk was of flowers and vows as the six couples spent the day tanning in the hot Mexican sun.

However, Jennifer did not appear to be wearing her massive eight-carat engagement ring, estimated to have cost Theroux $500,000.

Diffusing all pregnancy rumours, the blonde Friends star flaunted her toned stomach and natural born assets in a black string bikini and pink sarong as she relaxed.

Meanwhile, her 41-year-old beau eerily resembled Aniston's ex-husband Brad Pitt in Fight Club.

Relaxing with famous friends: The pair were joined by British actress Emily Blunt, who reclined on husband John Krasinski and Jimmy Kimmel and his fiancée Molly McNearney

Fiesta friends: Jennifer often turns her Cabo vacations into group affairs, and Thursday was no different

Coordinated couple: Jennifer later wrapped her pink sarong around her chest while her dark-haired beau flaunted his biceps in a black muscle tee

The Mulholland Drive stud looked tan, oiled, and ripped wearing nothing but a pair of grey jean shorts, rather than traditional swim trunks.

With his six-pack and sculpted pecs on display, it was also easy to view the assorted tattoos covering his muscular form.

Justin, who's the screenwriter behind Tropic Thunder, Iron Man 2, and Rock of Ages, flipped through a script while reclining on the sun lounger.

Bathing beauty: The 43-year-old actress flaunted her toned stomach and natural born assets in a black string bikini and pink sarong

Aside from the coy fish and bird on his back, Theroux has a grim reaper on his shin, the Black Flag logo on his knee, and a pair of scissors on his wrist.

The engaged couple arrived by private jet on Sunday to the Baja California peninsula famed for its sandy beaches, world-class scuba diving, distinctive sea arch, and abundant marine life.

Of course, a trip to Cabo is an annual tradition for the actress, who has taken her friends Chelsea Handler and Courteney Cox with her in previous years.

See the resemblance? Meanwhile, her 41-year-old beau eerily resembled Aniston's ex-husband Brad Pitt in Fight Club

Inked and ripped: With his six-pack and sculpted pecs on display, it was also easy to view the assorted tattoos covering his muscular form

Despite her knock-out shape, the Golden Globe winner, 43, recently said she quit dieting.

'I stopped dieting when I figured out that you just have to ear regularly and properly within moderation,' Jennifer told Britain's OK magazine in October.

'The fads are too much. I think it's really about being happy and smiling and laughing a lot.'

Has a way with words: Justin, who's the screenwriter behind Tropic Thunder, Iron Man 2, and Rock of Ages, flipped through a script while reclining on the sun lounger

Rebel: The Mulholland Drive stud looked tan, oiled, and ripped wearing nothing but a pair of grey jean shorts, rather than traditional swim trunks

After a year of dating, Justin popped the question to the Office Space funnywoman during his 41st birthday dinner at a New York restaurant last August.

Aniston and Theroux celebrated the holiday season by throwing a star-studded party earlier this month. 

Demi Moore, Ellen DeGeneres, Portia DeRossi, Tobey Maguire, and Ben Stiller were all said to have attended their Beverly Hills mansion soiree.

She loves Mexico: A trip to Cabo is an annual tradition for the actress, who has taken her friends Chelsea Handler and Courteney Cox with her in previous years

The motorcycle-loving actor is slated to direct and write the sequel to the 2001 film Zoolander and will also direct and rewrite the script for the upcoming 2013 movie Swear to God with Steve Carell and Will Ferrell as the leads. 

Aniston will appear in an untitled Elmore Leonard crime-comedy alongside John Hawkes and Mos Def.

In October, Jennifer wrapped her role in The Millers alongside Jason Sudeikis, Ed Helms, and Emma Roberts.

In the dark comedy, due out August, Aniston plays a hooker who poses as Sudeikis' wife in order to ferry 1,400 pounds of marijuana from Mexico to the US.

Set to marry: After a year of dating, Justin popped the question to the Office Space funnywoman during his 41st birthday dinner at a New York restaurant last August