Anita Sanz is a licenced psychologist, when asked what sort of things people of her profession know that regular people don't, she took to Quora to discuss happiness.
You don't really know how happy or sad something is going to make you in the future, even though you think you do right now. Put another way, psychologists know that most people are very bad at being able to predict how they will respond to positive or negative events in the future.
People will predict they are going to be happier about getting a raise or a promotion, finding a partner, or purchasing their dream car or house than they actually end up being when that event occurs. This can lead to feelings of disillusionment or disappointment when reality doesn't match the predicted level of happiness. Things rarely end up as good as people think they will be.
Alternately, people predict they are going to be more devastated by losing their job or a loved one or enduring a natural catastrophe than they actually are when that negative event occurs. Many people are surprised that when the worst thing they can imagine actually happens to them, they are rarely as bad off as they thought they would be.
Most happiness researchers (like Dr. Dan Gilbert) believe that there is a “happiness set point” for most people, and regardless of positive events (winning the lottery) or negative events (losing your home), a person will generally settle back to their own personal happiness set point, which may be higher than some or lower than some.
If the happiness set point explains why people can't predict what will make them happy or sad, other psychologists, like Dr. Martin Seligman, suggest that in order to be happier, instead of chasing the elusive and ultimately disappointing thing you thought would make you happier, you have to try to nudge your set point up a point or two, and yes, it can actually be done.
How this knowledge about people being such poor predictors of how they will respond to positive or negative life events plays out for this psychologist: I continually work with my clients (and remind myself, as well) that happiness is most likely to be found in this moment, not in any future one regardless of happy plans, goals, and dreams being pursued. And imagining future catastrophes turns this moment into an unhappy one, perhaps more negative than it would actually be if the catastrophe were to actually occur.
As John Milton said: “The mind is a universe and can make a heaven of hell, a hell of heaven.” We psychologists can help people to use their minds to make their present moments better than they could ever predict their futures to be.