There's nothing wrong with playing small - it's better than not playing at all. High expectations for success can lead to anxiety and procrastination. Playing small can break the cycle.
Many individuals suffering with depression actually seem pretty happy. They have powerful careers, happy families, active social lives, and seem to have it all pretty well together. Their positive, successful exteriors hide the real truth; that inside they are struggling with a daily battle against fatigue, low mood, frustration, and that self-critical little voice constantly telling them they are no good and dragging them down.