In your brain, bad trumps good every time because of this negativity bias. Your mind gives more importance and reacts more intensely to unpleasant experiences than to pleasant ones. Studies show that people will do more to avoid a loss than win an equivalent gain. Relationships need five positive interactions to balance out one negative.

When you experience one of these daily annoyances, your brain’s amygdala, the fear center, reacts as if you were being chased by a lion, activating your fight-or-right response. The amygdala sends alarm signals to your hypothalamus and your sympathetic nervous system, causing cortisol, adrenaline, norepinephrine and other stress hormones to be released. The amygdala also alerts your brain’s hippocampus, largely responsible for memory, to prioritize the upsetting event for storage.

Over time, negative experiences pile up and condition your amygdala to become progressively more sensitive. Feeling stressed, anxious, negative or angry today leads to being more inclined to feel that way tomorrow and so on. The cortisol in your brain overstimulates, weakens and eventually kills cells in your hippocampus, shrinking it. In addition to assisting with memory, the hippocampus calms down your amygdala and tells your hypothalamus to quit producing stress hormones.

These biological tendencies are further amplified by other factors, like personality traits and traumatic life experiences or circumstances.

Your brain evolved to be reactive for good reasons, but this hurts more than helps today.