When Christina Aguilera burst onto the scene in 1999 with her debut self-titled album, she was just 19 years old. Now, she has an incredible career with seven albums under her belt, and back in August 2015, she gave birth to her second child. Also, if her appearance on The Tonight Show Starring Jimmy Fallon taught us anything new, it's that Christina is really, really good at pop star impressions. We thought it was high time we look back at her incredible transformation through the years, as well as the inspiring quotes about body image she's shared along the way. Keep reading to go all the way back to 1999.