There is no joy like the resolution of doubts (Tzel HaMaalos, 38).
Many people's insecurity leads them to suffer from self-doubt. They are never certain about what they should do or whether what they have done is right. While this degree of doubt may not be so intense that it renders them incapable of making decisions (and therefore requiring psychiatric care), it can cause them enough distress to prevent them from enjoying life.
Self-doubt is one aspect of low self-esteem. Somewhere in these people's past, they failed to develop trust in their capacity to make good judgments.
All of us must make many decisions every day. Since we lack prophetic foresight, we cannot predict the outcomes of our decisions. Our control of events is limited. We should realize that all we can do is to take the best information available and be sincere in trying to do what we believe is right.