Fergie is feeling nostalgic as she celebrates another year around the sun. On Thursday, March 27, the "Big Girls Don't Cry" singer marked her "landmark" 50th birthday with a letter to her younger self on Instagram. "Dear little Stacy, one day you’ll be 50 and you’ll be proud of yourself. You won’t have it all figured out, but you realize …. who does? Success really is in the journey, and true happiness can be found in the smallest simple moments," she wrote alongside a photo of herself as a child. Fergie continued, "Keep loving deeply with all your heart, and keep working on yourself. It always all makes sense later. I love you." In the second slide of the carousel, Fergie included Billboard's recent top women artists of the 21st century list, which featured her in the 28th spot. "I added the Billboard chart because I wanted to say THANK YOU. (thank u really tho;) It was a beautiful surprise and really made me feel like my music means something," she wrote, referencing the lyrics of her hit "Glamorous." In the final slide, she included a photo of her son Axl Jack, who she welcomed with ex Josh Duhamel in August 2013. "I also could not acknowledge this milestone without including my son Axl Jack, the sweetest love I’ve ever known. You make me want to be a better human every day," Fergie wrote. She then signed off her post, writing, "Onward and upward🎂🎂" Fergie has largely kept out of the spotlight in recent years, only sharing snippets of her life on Instagram from concerts, football outings and life with her son. In August, Fergie marked Axl's 11th birthday on Instagram and included shots of him throughout the years. "Happy 11th birthday, Axl Jack!" Fergie wrote in her caption. "It is so fun watching you grow in every phase of your life." "Seeing soccer through your eyes makes me feel like a kid again. No matter what jersey you’re wearing I’ll always be your biggest cheerleader for anything you want to do in life. I love you beyond words ♥️ ♥️." Meanwhile, in January, rising musician Sturdyyoungin, Ohthatsmizz and Zeddy Will sampled Fergie's "Clumsy" and created "Trippen," which she starred in the music video for. Fergie celebrated the release on Instagram and shared the music video, where the "Glamorous" singer appears as a school teacher while the three rappers play football players in pursuit of the cheer captain. She also shared behind-the-scenes photos and videos here. "I’m so proud of these boys and grateful to @sturdyyoungin_ for breathing new life into Clumsy. “TRIPPIN” song and video out today. 🤓🤓," she wrote. Fergie released her most recent studio album, Double Dutchess, in 2017. Her debut album, The Dutchess, was released in September 2006.