Demi Lovato is celebrating six years of sobriety.

The 25-year-old singer - who has previously struggled with substance abuse and self-harm - has taken to her Twitter account to celebrate reaching the milestone and to tell her 55.5 million followers that they too can overcome their own problems in life.

Demi wrote: ''Just officially turned 6 years sober. So grateful for another year of joy, health and happiness. It IS possible. [praying emoji] (sic)''

Demi previously admitted that, as part of her battle against alcoholism, she's been forced to give up partying because it can trigger her cravings.

She shared: ''I had to learn the hard way that I can't do parties anymore.

''Some people can go out and not be triggered, but that's not the case for me.''

And while Demi admits that her new life sounds ''boring'', she's happy to make the sacrifice in order to maintain her own well-being.

The 'Sorry Not Sorry' hitmaker - who starred on the children's TV series 'Barney & Friends' as a child - explained: ''I know [my life] sounds so boring.

''But I've come to a place where I'd rather be relaxed than get all dressed up and go to some party or club with people who don't really care about my well-being at all.''

Meanwhile, Demi recently admitted to being frustrated by the diet culture in America.

The curvaceous star has been a long time advocate for body positivity and she hates how society is ''constantly telling us we're not thin enough''.

She wrote on Twitter: ''It's so frustrating and sad how strong the #dietculture in our society is. It's constantly telling us we're not thin enough no matter what. You are beautiful no matter what anyone says. (sic)''