Before throwing a holiday party with Justin Theroux for her celebrity friends on Dec. 8, Jennifer Aniston looked stylish while heading to a spa on Dec. 6: See the picture! Credit: AKM-GSI

No spa treatments needed! Jennifer Aniston looked radiant and stylish while going to an L.A. spa on Friday, Dec. 6. The 44-year-old dressed incognito in a black fedora hat and shades, but her beauty still shined through.

Aniston flashed a big smile to photographers during her outing. The Friends alum wore a tucked-in blue dress shirt, black skinny jeans and black booties. Her new bob haircut was only slightly visible under her hat, but her huge engagement ring from fiance Justin Theroux was on full display.

The We're the Millers actress was likely primping for her annual holiday and tree trimming party. The actress threw this year's bash for her A-list friends at her Bel Air home on Sunday, Dec. 8. Celebrity guests included Gwyneth Paltrow and husband Chris Martin, Courteney Cox, Robert Downey Jr. and wife Susan, Jason Bateman, Tobey Maguire and wife Jennifer Meyer, Isla Fisher, Will Arnett and Chelsea Handler.

Aniston and Theroux, 42, who got engaged in August 2012, were photographed preparing for their party by buying a Christmas tree together at Mr. Greentrees in Beverly Hills on Dec. 5.

"They spent about five minutes [looking at trees] before deciding on a big noble fir," an onlooker told Us Weekly. "Jennifer knew what she wanted and was leading the way. She was smelling the trees and seemed very into the holiday spirit."