Several people we've profiled in our Voices of Mental Illness series have said that undergoing cognitive behavioural therapy marked a turning point in their ability to deal with their illness. In fact, several people cited it as the reason they chose not to commit suicide. We asked Dr. Zindel Segal, head of the Cognitive Behaviour Therapy Clinic at the Centre for Addiction and Mental Health (CAMH), to explain why cognitive therapy is making such breakthroughs in the treatment of mood and personality disorders. This look into cognitive behavioural therapy is part of TVO's Mental Health Matters series - an in-depth exploration of the state of mental health in our society.