Demi Lovato may only be 21 years old, but she's already experienced a lifetime of ups, downs, heartbreaks and addictions.
Having struggled with self-esteem issues and spent many months in rehab, the singer now tells Cosmopolitan that she wants to serve as an example to others who can relate to her plight.
"When I was younger, I needed someone in the spotlight to idolize, who stood for positivity and light and happiness, and wanted to change the world," she tells the publication.
"And because I didn’t have that, I realized, I want to do that, if only for my 12-year-old little sister."
Lovato is walking the walk as well.