So here's the tragedy. Everyone might think being mentally ill is a decision, and not a disorder.
Imagine you broke a leg, and someone tells you, it's not really broken, they tell you it's broken because in your mind you have the opinion that you have a broken leg. Ok, that sounds crazy. If you have a broken leg and someone asks you to run in a race but gets disappointed because you refused to would make anyone mad.
That's how a person with mental illness feels every single day.