Stress not only occurs in the negative situations but also arise in positive event such as getting married, moving into a new city, or starting a new job. Therefore, stress possibly comes after either positive or negative event and results in the development of depression.
Techniques
Many of us experience depression because of certain misfortunate situations that occur in day to day living, but somehow we manage to survive.
Maybe, because our minds are chemically balanced or because we are emotionally strong, we have survived, but remember the next time when you are depressed about a particular misfortune that it's okay ...