Christina Aguilera gets reflective on her 40th birthday.

On her 40th birthday (Dec. 18th), Christina Aguilera opens up about embracing the aging process and ignoring the "stigma" of getting older. 

Her heartfelt note about embracing the aging process was posted to Instagram, and she posed for a new photoshoot to celebrate the new milestone. 

For some people, life starts at 40. In 40 short years, Christina has lived THAT life and endured so much more than most people have in their entire lifetimes. Happy birthday to this underrated pop icon!!!!!