If you can "reframe" a circumstance that makes you feel bad, you won't feel bad any more. Nothing has changed except how you're looking at it, but that's enough to change your feelings. Reframing means interpreting the situation differently. When something happens, you interpret it a certain way, and your mind usually does it automatically. The situation just seems a certain way to you, and you have feelings appropriate to the way you look at it.
For example, a few months ago I had to go to the dentist. I noticed I felt a little grumbly and nervous about it. In other words, I was in a bad mood about it. I realized the "frame" I was using to interpret this event was: "I have to go do this unpleasant thing." And my feelings were appropriate to that interpretation. I dreaded going and felt annoyed that I had to go.
So I asked myself, "Is there another way to look at this?" And instantly I realized that in most of human history, dentists didn't exist. People had horrible toothaches and couldn't do anything about it. Their teeth rotted out, and nothing could be done. Even a few hundred years ago, most of the "dentistry" consisted of pulling out a tooth that was causing pain (and pulling it out without novocaine!).
But I go to a very clean environment and my teeth are professionally maintained. Because of this, I'll probably have my teeth my whole life. My dentist goes out of his way to keep pain to a minimum. From this perspective, which is just as valid as my automatic interpretation, I am lucky to go to the dentist.
When I thought about it that way, my mood shifted. I felt better. I felt fortunate to live in a time when people can take care of their teeth. I felt lucky to live in a place where we have dentists.
That's how reframing works. It is surprisingly easy to do. All you have to do is 1) notice some circumstance is bringing you down, and 2) ask yourself if there is some other way to look at it than the way you automatically look at it.
Read another article about it: How to Gain Perspective.
Read a book about it: Viewfinder.