Britney Spears is celebrating her 40th birthday in style!
The pop star turned 40 on Thursday, and marked the occasion with a festive getaway to Cabo San Lucas, Mexico with fiancé Sam Asghari.
"I'm so blessed and grateful !!!! Tears of joy today," Spears wrote on Instagram, adding a crying emoji. "Thank you for all the b-day wishes 🥳🎂🎈🎉 !!!! Psss I didn't even drink the champagne 🥂 no lie !!!!"
Spears accompanied her message with a video set to a remix of the Madonna song "Frozen" that began with an impressive array of balloons spelling out "Happy Birthday Britney."
She then showed off a rose-topped cake in the shape of a "B" that was served with a glass of freshly popped champagne courtesy of Asghari, 27, who was clad in a plaid shirt and sunglasses.
The video then featured Spears enjoying the music of a mariachi band as someone handed her a giant cupcake with a sparkler on top, and later a series of fireworks.
A source told PEOPLE that the "Gimme More" singer was thrilled to enjoy a getaway with her "biggest supporter" Asghari.
"Britney was very excited," the source said of the trip. "She loves beach vacations and hasn't been to Mexico in many years… She is doing well. She is taking care of herself both physically and mentally."
Spears herself said as much in an earlier Instagram post on Thursday that celebrated her romantic getaway, which comes after her 13-year conservatorship ended on Nov. 12.
"Oh the precious joy today !!! Me and my fiancé are so excited to be going away," she wrote alongside a photo of her hugging Asghari in their private jet. "God thank you for being able to go out of the country !!!! I am blessed !!!!"
Kevin Winter/Getty Britney Spears and Sam Asghari
Asghari also shared the same photo, writing: "I call you Lioness because I admire your relentless strength, I'm inspired by your beautiful heart, I celebrate your smile that lights up my world ❤️," Asghari wrote. "Everyday is your birthday my queen 👑"
He added, "Happy 1st birthday to my wife 🥳 #dec2nd@britneyspears."
The couple announced their engagement in September, after more than four years of dating. A source previously told PEOPLE that the two are in the planning stages of their wedding.