42+ Mental Illness Strength Quotes. Fisher, who received her bipolar diagnosis at 24 but didn't really ac. Can we nail down what the causes of mental illness are? Learn more from webmd about the causes of mental illness, including biological, psychological, and environmental factors. Subscribe to our free newsletters to receive latest health news and alerts to your email inbox. Mental illnesses interfere with your relationships, your work, your sleep, your daily feelings of contentment, or if it negatively impacts someone else. How can you tell if you are mentally ill? The modern world places a great deal of importance on physical health, emotional health, and even financial health. When it comes to mental health? What are the causes of mental illness? Mental illness is a broad term, but are its causes equally broad?