• Sam Asghari surprised Britney Spears with a four-day trip to Mexico for her 40th birthday
  • The singer shared photos and clips of her birthday celebration on Instagram
  • Asghari's surprise included a massive balloon display with Spears' name spelled out and a serenade from a mariachi band

Britney Spears let her fiancé Sam Asghari know she appreciated his efforts to make her birthday extra special.

Spears has a lot of things to celebrate this year — her engagement, the termination of her 13-year conservatorship and her 40th birthday. The pop superstar turned another year older Thursday, and Asghari surprised her with a romantic four-day getaway to Cabo San Lucas, Mexico, to celebrate.

The "Toxic" singer shared photos and clips of her birthday celebration on Instagram, which included a massive balloon display with her name spelled out and a serenade from a mariachi band, among others.

"She hasn't been to Mexico in a long time and thought it was the perfect place to ring in her 40th birthday. Sam went all out it to make it special for her and to let her know how much she is loved," an unnamed source told E! News, adding that the couple stayed at a beachfront suite at the Las Ventanas resort.

The couple was welcomed by mariachis and festive décor upon their arrival. On the morning of her birthday, he surprised her with balloons, flowers and a beautiful cake, according to the source.

Spears loved her fiancé's surprise, with the tipster telling the outlet, "She seemed very appreciative of Sam and was always showering him with kisses and hugs."

During the trip, the pair also spent time working out in the gym, hanging out in their room and soaking up some sun at the beach. They also walked down the beach for a tanning session before later enjoying dinner for two and fireworks over the ocean.

On a different day, Asghari and Spears "rented a yacht and sailed around the bay at sunset," the source said.

According to the onlooker, the singer looked "very relaxed and happy" throughout their trip. "She was giggling, dancing and really enjoying herself. She had a great trip to Cabo and a big smile on her face," the source added.

Spears and Asghari announced their engagement in September after nearly five years of dating.

The singer shared the happy news by posting on Instagram a video of her showing off her diamond engagement ring. In the clip, Asghari asked her, "Look at that. Do you like it?" She replied, "Yes!"

An unnamed source told Page Six at the time that Asghari wanted to spoil her with a "very special, over-the-top and meaningful proposal." The personal trainer popped the question with a ring that has a 4-carat round brilliant stone and has Asghari's nickname for Spears, "Lioness," engraved inside the band.

According to the insider, both Spears and Asghari wanted to start a family of their own in the future. "He dreams of one day becoming a dad too, and Britney, of course, has always wanted to have more kids, especially now that hers are getting older," the source said.

Spears is a mom to sons Sean Preston, 16, and Jayden James, 15, whom she shares with ex-husband Kevin Federline.

Britney Spears
A report which said Britney Spears was secretly engaged and was planning to use surrogacy for a third child was debunked by Gossip Cop. In this image: Spears (L) and Sam Asghari attend the 29th Annual GLAAD Media Awards at The Beverly Hilton Hotel Beverly Hills, California, April 12, 2018. Getty Images/Vivien Killilea