You are a negative person. Not just you, but also everyone you know. The human brain responds more strongly to negativity, so it affects us more easily. When a negative event ruins your day, cure it with a happy one.
Several studies suggest that brain reacts much more strongly to negativity, based on a comparison of the electrical activity caused by both negative and positive stimuli. If you've ever had a really good day ruined by a bit of bad news, you've experienced this before. Hara Estroff Marano, over at Psychology Today, explains how heavy this negative bias really is and its real-world effects:
Because of the disproportionate weight of the negative, balance does not mean a 50-50 equilibrium. Researchers...have found that a very specific ratio exists between the amount of positivity and negativity required to make married life satisfying to both partners. That magic ratio is five to one. As long as there was five times as much positive feeling and interaction between husband and wife as there was negative, researchers found, the marriage was likely to be stable over time. In contrast, those couples who were heading for divorce were doing far too little on the positive side to compensate for the growing negativity between them.
So what can you do to counteract your negative bias? Little things. Big, exciting, positive stimuli are great but don't have enough of an effect to counteract negative stimuli. If you compound lots of good — but small — things, you may be able to positively stimulate your brain and turn your day around.
Our Brain's Negative Bias [Psychology Today]