What Is Depression Depression is a mental condition that creates a constant feeling of sadness. You lose interest in activities that you once enjoyed. It is also known as major depressive disorder. This is a condition that has an impact on a person’s feelings, thoughts, and behaviours. It can be a contributing factor that affects mental as well as physical health. You can have issues performing typical day-to-day activities. And at times you might feel that life isn’t even worth living anymore. Thus, it’s important you learn how to deal with depression.