Daicy, this may not be what you had in mind, but I often wonder how much of my suffering comes from a "mental illness, i.e. genetics/brain chemistry out of whack, etc. or whether a significant part of my suffering is optional, that is, a product of a lifetime of negative beliefs about myself, that are nearly constant and often subliminal and rapid fire in my mind. Unfortunately, the latter theory leads me to more self-blame ("Well, stop that thinking!"). It's not a useful or answerable question, although it obsesses me. The underlying question is what do I have control over? Most likely, it's a combination of factors anyway.