There really are differences between people in whether they see the glasses around them as half empty or half full. Often, this has to do with what the motivation psychologist Tory Higgins has called a regulatory focus.
The human motivational system has two modes: an approach mode and an avoidance mode. The approach mode engages when people are interested in some positive or desirable outcome in the world. The avoidance mode engages when people are attempting to evade a negative or noxious outcome.
The idea behind a regulatory focus is that when pursuing a particular positive outcome, people often become more sensitive to positive outcomes in the world more generally. The see all the glasses around them as half full. This orientation is called a promotion focus.
Conversely, when pursuing a particular negative outcome, people often become more sensitive to negative outcomes in the world more generally. That is, they see the glasses around them as half empty. This orientation is called a prevention focus.
There is also a personality trait related to these regulatory foci. Some people are generally promotion focused. All else being equal, they tend to focus on positive outcomes. As a result, we think of them as optimists. Other people are generally prevention focused. They typically see negative outcomes, and we call them pessimists.
If you’re one of those pessimists, you probably think you’re doomed to be a pessimist forever. That would be the pessimistic approach.
But there are some things you can do to try to flip your motivational orientation.
Focus on what you want
The easiest is to focus yourself explicitly on a goal related to a positive outcome you’d like to achieve. The more you engage with great things you’re trying bring about, the more that you will also naturally notice other good things in the world and opportunities to find benefits. This optimism comes along for free when you’re looking to create a positive outcome.
Hang out with an optimist
If you can’t find anything desirable you want to focus on, you can look for an optimist to hang out with. There is a lot of evidence that we tend to tune ourselves to the people around us—particularly those people we converse with. Successful conversation involves predicting what your conversation partner wants to say. If you hang out with an optimist, then you are going to look for positive things in the world, because they are likely to talk about them, so you are going to want to notice those same things, so that you’re prepared for topics they will bring up.
The last thing to do is to recognize that even your inner pessimist has a hidden optimist. Often, pessimists take a (somewhat perverse) joy in having their worst fears confirmed. So, pessimists are optimistic that their worst fears will be realized (and that they will get the chance to say “I told you so”).
Once you realize that you have an optimist in there (albeit one that wants to see things go wrong), you can try to reorient that tendency to also take some joy in things that go right. It may be effortful at first to enjoy the things that are going right. You might even want to give people around you permission to point out when you’re going negative (yet again). But, personality characteristics are not destiny. You can learn new habits to find desirable things around you and to revel in them.