A psychic prison is an ugly thing. The good news is that you have the key to get out - since you were the one to imprison yourself in the first place.
The are two common types of psychic prisons: emotional and mental.
If you cannot discard your own thoughts easily and if you attribute much importance to them, your own patterns of thinking can become a mental psychic prison. If your mind is not open, you can see things only one way and that can be very frustrating.
If you lack the self-discipline to control your emotions, your emotions will control you and this is a form of emotional prison. It feels like your existence is limited, and many people try to escape it by increasing physical action to feel something different - generally without success. Without developing self-discipline and taking control of yourself, this prison is almost impossible to escape.
These psychic prisons can range from small obstacles that you seemingly cannot wrap your head or heart around, to full-blown existential problems that manifest as physical, bodily illness and severely hinder day-to-day life.