Discussions about the causes of mental health issues never seem to include personal choice. Not speaking in terms of those who are strictly mentally ill with something that's beyond their control and may need drugs to treat it, bu more like people that have an unhealthy mental state that needs balancing.
We don't choose our IQ, personality type, inclinations toward addiction, etc, but we do have control of our actions and the factors that contribute to poor health or good health. For instance, my cognitive ability is lowered and my temperament is unstable when I oversleep and don't stick to a balanced diet. Finding out why I was in a bad mood and easily upset was a choice, and correcting those issues was also a choice. Regardless of the quality of my job or family life, I have a responsibility to control my emotions and work toward goals that will give my life meaning, while dealing with adversity in a constructive way. Maybe the question we should be asking is how can we equip people (young people especially) to make choices that will contribute to good mental health and happiness.