There is a three fold cord within us, our mind, our body, and our spirit. Our mind has the conscious and the unconscious, in other words that which we are aware of and that which operates in us but works without our decision making process (hand get onto a hot plate, immediate response from the mind is to remove that hand fast within fractions of a second). Our body has an interdependency within itself, in some circumstances compensating for one another. The spirit is our source of life, without it we are just a bio-mechanism. Our feelings are within the controls of the mind. If I hurt, the brain/mind begins to regulate that pain thru chemical processes. In addictions an external chemical disrupts the chemical function of the brain, and alters the conditions under which the brain responds in thought and feeling.
Depression is referred to as internalized anger, my thoughts are I can not express my anger AND let it go. Another way to look at it is, I hurt, therefore I'm angry (could be towards someone), I choose to let it go (forgiveness)... which leads to a release of negative energy and an increase towards positive action... towards others as well as for yourself. Even though one feels an emotion, one can gain control over it... thru your words. Consider positive affirmations ( that's what many scriptures are, your reassurance that you are a child of the Living God ) The combination of the natural and the supernatural, mind and spirit... faith. Your Highest form of being is thru faith (your thoughts, I can do all things thru Christ that strengthen me) to experience Love (most productive emotion, the presence of God). Because none of us are perfect, there is always a need to forgive, and that forgiveness heals us... we let go of the negative, that which consumes us, and move forward for each day is a new day.