Rocstar / Fame Flynet 1 / 10
Rocstar / Fame Flynet 1 / 10

Single life -- it does a body good if you're Gwyneth Paltrow.

Apple and Moses' mama showed off her fit physique on Jan. 16 as she wore a cream-colored string bikini while hanging out in Mexico at a friend's birthday. The "Mortdecai" star's children splashed around in the water as Gwyneth and her toned abs took in some sun.

RELATED: Gwyneth's monochromatic looks

The weekend getaway in Punta Cana was for Gwyneth's friend Crystal Lourd, who celebrated her 50th birthday with other celebrities Joe Jonas, Chord Overstreet and "Full House" alum Lori Loughlin.

RELATED: Hottest bikini bodies 40 and over

Gwyneth, a source told Us Weekly, "was drinking margaritas" and "dancing on the beach".

RELATED: Gwyneth reveals the hardest drug she's ever done

But although she's toned and athletic now, that wasn't always the case for the "Iron Man" star. In August 2013, her longtime trainer Tracy Anderson told beauty website Into the Gloss how she whipped the actress into bikini shape.

"Gwyneth is lucky because she's really tall, so she can hide it really well in clothes, but she had significant problem areas," Tracy said in 2013. "I felt so badly for her, and thought I could really help. So I agreed, and she did everything I asked. Now, seven years later, she looks younger every year; she's totally transformed."

Tack on a few more years, Tracy, because two years after those comments, Gwyneth is still looking young, transformed and better than ever!