When i told my first therapist that i had panic disorder, she told me that panic disorder was the worst mental illness you can have, because it literally feels like you are dying. Panic attacks are indescribable, and while i am not saying they are the worst mental illness out there, they were the worst feelings I've ever felt in my life. I literally felt like i had descended into hell and was fighting off demons. I either felt like I was dying, or that I wanted to die to get rid of the agony of the attacks. My panic attacks would happen several times throughout the day, and lasted for 6 months before i ever figured out what it was. That it was just a panic attack, and nothing seriously physically wrong with me, other than a chemical imbalance in my brain. Just putting my 2 cents in. I think any illness where you don't know what it is, ie when i didn't know i was having panic attacks, and thought i was literally dying, is the worst. Once you can name the disease and know what's really going on, its easier to cope with.