Without rational self-direction, we would be lost, driven only by the dominant instinct or need of the moment. Learning to organize and control our lives is necessary to get where we want to go. We may not always give fantasy the credit it deserves but our mind is almost constantly rehearsing how to handle some difficult situation. We imagine what we could say and do, and how others might respond, and how we could react to that, etc. Rather than just stopping giving self-instructions, it is sometimes helpful to give the wrong instructions, as in paradoxical intention.
Life is more than just avoiding problems.
We must reserve our energy for planning and carrying out positive, meaningful, moral tasks and missions. We can hardly solve a problem if we don't admit we have one. Indeed, some efforts aimed at reducing stress might interfere with finding permanent, complete solutions, e.g. if we used drugs or relaxation to reduce stress, we might be less motivated or inclined to explore the underlying causes of the distress and do something about the true causes. These positive beliefs are based on what worked for us in the past, on observing or talking to or getting support from others, or on learning new skills and knowledge. If we are blessed with a sense of humor and if we can see the smallness of ourselves and our problems, it is helpful.