Thinking possitively is difficult. A large part of it is to do with that internal dialogue, or self talk. You have to actually talk yourself into a positive outlook and tell yourself to stop when you’re thinknig destructively.
There are several destructive thought processes (if you google it, you’ll find articles that I’m sure you may realise you do, and how to avoid them). When reading about psychology of depression, one thing that stuck in my mind was when interviewing people who suffered from depression, they found that when asks questions about aspects of their life in general (as opposed to specific occurances) they were more positive.
So basically when you are thinking about a subject (love, your work, academia, etc), try to avoid thinking about specific occurances and more about your experience as a whole over your life.
There are certain thought processes you should avoid, like dwelling on regrets. Never play the ‘what if’ or ‘if only’ game (eg- if only I had done this, if only that hadn’t happenned). Think more proactively (what can I take/learn from that experience to avoid it in the future, what can I aim for, what good things are on the way).
Getting out of a negative thought process is difficult. The cognitive processes mean that if you experience one failure or bad experience, your brain automatically starts thinking of any other failures/experiences and failing to think of the positives (this is physical because your brain actually stores associated information together). It’s the same on the other side; thinking about personal successes/positive experiences will remind you of other positives.
Tests have been done where participants were given some arbitry test and were either told that they did well or badly (regardless of their actual result) then left on their own for 20 or 30 minutes. After that time, a tester would come in and tell them that what they were told was a lie and that their given results were completely random and unrelated to their actual performance. They were then asked how they thought they really would have performed and those givent he false negatives still thought they would have done badly and vice versa, despite the fact that they’d been told it was a false result.
So you can force yourself to be positive, you just have to force yourself to think about all the times you acheived something, or good things happenned to you and not negative things. You will end up optimistic and happier.
Finally, the hardest part about negative thinking is self fulfilled prophecy. This is another aspect of pschology. Someone who thinks negatively or is pessimistic about something will be looking for aspects of a situation (or person, etc) to prove their belief.
There has been testing done with this, where participants would be told that another participant was an introvert and pessimistic, and others would be told the opposite, and when different members met the same person, they were asked afterwards what they thought of them, and they correlated with what they were initially told.
Basically my point is, in short, negativity breeds negativity and positivity breeds positivity. It’s an actual cognitive process. The hardest part of getting out of a depressed or negative outlook is the first step, and once you start being positive it will perpetuate itself.
Focus on your successes and positive experiences. Tell yourself to stop when you start thinking negatively. Happiness truly is a state of mind.