At its worst, depression can be a frightening, debilitating condition. Millions of people around the world live with depression. Many of these individuals and their families are afraid to talk about their struggles, and don't know where to turn for help. However, depression is largely preventable and treatable. Recognizing depression and seeking help is the first and most critical towards recovery.

In collaboration with WHO to mark World Mental Health Day, writer and illustrator Matthew Johnstone tells the story of overcoming the "black dog of depression".

Watch the video from the World Health Organization.