Our bodies make all the chemicals necessary to create either stress or profound well being. Our intentions and focus has a lot to do with what chemical cocktail we are creating. Personally, I like the expanding ones.
Dr. Joe Dispenza addresses a lot of this and how people are addicted to stress in his book Breaking the Habit of Being Yourself. Adrenaline, cortisol and others give the body a rush and people become addicted to them. I have been there and know the power of these chemicals and hormones. I have learned through years of daily breath work and meditation to tame the drama and have come to a place of activating what I call the joy cells.
Joy cells have the power to turn on and off our DNA expression-to halt disease and turn on vitality and wholeness which is our natural state. It is then that life has a purpose larger than ourselves. It is then that we feel so whole and complete that our happiness is generated from within instead of from our outer environment. It is then we become free and abundant, our joy cells dancing in coherence.