Everyone is talented but not skilled. Different people have different abilities at different levels. Since many of us are not skilled, we underestimate ourselves as dumps. We think we are not fit for the job, disregarding the fact that it is all about the lack of skills, not the talent. Since any skill can be learned, it is a matter of investing time to learn them. It takes hours and hours and hours of practice to be skilled. Our talent shines once we learn the right skills.
If you are depressed, never try to find out why you are depressed, instead, try to find out why did you choose to interpret the situation that led you to the depression. It is never the situation, but always the interpretation, which is responsible for the depression. So try to interpret it from a different angle to lift up your mind. It works!