In 2010, the former Disney star and current ''X Factor'' judge hit bottom amid reports of bipolar disorder, cutting, and drug use; now 21, Lovato shares advice from her recovery in ''Staying Strong,'' a book of daily inspirational thoughts

A lot of your peers like to say, ”I’m not a role model.” But with a book of advice like this, you’re saying the opposite.
I used to say that too. That was my excuse to do whatever the f— I wanted and not give a s— about what other people thought. Then I ended up going through some stuff. I realized I’m never going to escape the fact that I’m in the public eye, so I might as well do the best I can.

You’ve been quite open about your personal struggles ever since they came to light.
When I went to rehab, I was still on the Disney Channel — I think I might be the first person who can say that! [Laughs] It wasn’t like I could discreetly make the choice to go into treatment. My actions were very public. My manager told me, “You can decide not to talk about anything, or you can be completely honest.” Now, at night, I can rest on my pillow easy because there’s nothing I’m hiding.

Was it scary making that decision?
When I was in treatment, I honestly thought my career was over. But when I came out of treatment, I had more supportive fans than ever. There are lots of artists who aren’t honest — they put on a face. Nobody can relate to that face. Growing up, I needed someone in the public eye to look up to. At the time, it was starlets clubbing and getting really, really thin. That’s what I thought was cool and glamorous. But now I want to inspire that young girl who thinks she’s overweight, or too thin, or not pretty enough.

You have a book deal for a real memoir. Have you started on that?
I haven’t. I’m battling with internal thoughts on how honest I should be. Yes, I’ve been very honest, but if people really knew how dark and deep my struggles got — not just with my eating disorder but with drugs and alcohol — they’d be really shocked. But I’ll most likely end up saying everything. Maybe it’ll help other people in the industry who are headed down the wrong path.

You and Miley Cyrus both started out on Disney but now have very different careers. What advice would you give her?
I’m in no position to give people advice on their careers. She’s having fun and figuring out who she is, and this is the age when that happens. I think that…[long pause and a smile] she’s doing her own thing. Good for her.

Now that you’re a published author, what do you want to do next?
Life is so short, and I have so many dreams. I even had dreams of becoming a prosecuting attorney. I told my management I was going to law school, and they said, “When?” I was like, “Maybe when I have a baby and things slow down.” They’re like, “That doesn’t make any sense!” I want to be a director, and I want to pass bills in Congress about bullying. I really, really want to have my own talk show one day — be the next Oprah. I really do want to save the world. I know that’s kind of impossible, but I’m striving for it.