Demi Lovato thinks it's "okay to have a mental illness"

She said: "I just think mental illness is something people need to learn more about.

"I want people to know it's okay to ask for help and it's okay to have a mental illness."

The chart-topping performer - who was diagnosed as bulimic, bipolar and addicted to drugs and alcohol in 2011 - explained that her father, Patrick, suffered from similar illnesses before he passed away in 2013.

She told PEOPLE magazine: "I watched him live a very unfortunate life because of the lack of access to treatment."

However, the 'Heart Attack' singer - who's previously spent time in rehab - revealed she's doing well in her own battle against addiction and mental illness.

She said: "I'm doing really well. I'm successful, but most importantly I'm healthy and happy, and I do not let my disease define who I am."

Demi gave special thanks to her boyfriend, Wilmer Valderrama, 35, saying he's been "so helpful".