God provides the quiet waters which we need to survive. Having the soul restored means that even though we are in the care of the good shepherd, we have times when we need restoration. Here the Hebrew word means to bring back home again, recover, refresh, relieve, retrieve, return. David said this because our soul needs to be restored, including our mental attitude. The mental attitude relates to your true personality and character.
Character is developed through experiences of trial and suffering.
However, the whole key is how you respond in your mental attitude, not how you react. Every trial endured and weathered in the right mental attitude makes a soul virtuous and stronger than it was before. Character is revealed by your mental attitude in times of adversity, hardship, disaster, and even tragedy. Winners do not become winners when they win an event, but in the hours, weeks, months and years they spend preparing for it. The victorious performance itself is merely the demonstration of their championship character.