According to neuroscientists, all thoughts cause some form of chemical release to occur in the brain. Therefore, serotonin, which is known to counterbalance cortisol, is often produced by the human brain when positive or joyful thoughts come to the fore. Cortisol is associated with stress, so producing more serotonin can help to alleviate bad moods, for example. In other words, you can think yourself into a more positive frame of mind.