Britney Spears is celebrating her 40th birthday in style! The “Breathe On Me” singer was seen on a yacht with fiancé Sam Asghari, 28, in Cabo San Lucas, Mexico on Friday, Dec. 3 — one day after her actual birthday. The blonde kept her lengthy locks back into a slick, high ponytail as she stood at the front of the boat, rocking a pair of aviator sunglasses. She appeared to be wearing a bright yellow swimsuit with a green shirt overtop in the snaps published by the Daily Mail.