Demi Lovato celebrated being six years sober on Thursday and sent out an inspiring message to her fans on Twitter. "Just officially turned 6 years sober," she wrote. "So grateful for another year of joy, health and happiness. It IS possible."

Just officially turned 6 years sober. So grateful for another year of joy, health and happiness. It IS possible. 🙏🏼

— Demi Lovato (@ddlovato) March 15, 2018 [1]

The 25-year-old singer has always been very open about her past issues with drugs and alcohol [2], but it wasn't until she released her latest YouTube documentary [3], Simply Complicated, that fans got a glimpse of her experience with addiction. Demi revealed she had tried cocaine for the first time at 17, and after that, she went through a stage where she was "using daily."

"In this documentary, I'm 1000 percent sober and I get to really explain myself and apologize to my fans. There wasn't anything that was off-limits," she told People in October 2017. "It's something I definitely feel relief from [4]. Being so honest and open and talking about subjects that I have never talked about before is a big part of why I feel relieved . . . I feel like I got to really speak my truth."