I remember being quite confused when someone told me that perception was reality and that happiness was something I already had, even though I was in the throes of depression. But I let it simmer for a while and tried to see if I could talk myself into happiness using positive thinking, the law of attraction and gratitude. Those are definitely useful tools, but the underlying unhappiness always seems to come back. And that's perfectly normal. According to this book, the Myth of Stress, heaping positive thinking on top of negative thoughts does not work -- changing your beliefs is your only hope. The book takes a cognitive approach to emotions with a basic belief that our thoughts are at the centre of our being. Shift your perceptions and suddenly everything is a little brighter. A good friend of mine is particularly adept at doing this -- challenge your beliefs by holding what you think makes you miserable under the microscope, put yourself in the other person's shoes, think of something worse and get yourself out of your funk.
I was a bit skeptical at first because everyone seems to have some kind of gimmicky methodology to sell that will fix your problems. But this book's tool appealed to my sense of logic and need for process. The exercise is designed to help you challenge stressful beliefs. You start by stating something that you think is causing you stress -- e.g. "She should see things my way". You write down how that makes you feel, how you react and rate the degree to which you believe the statement to be true. Then you negate the statement, preface it with "In reality, append "at this time" -- e.g. "In reality, she should not see things my way, at this time" and brain-storm all the reasons why that could be true. In this example "In reality, she should not see things my way, at this time because ... I could be wrong, she has a different set of experiences than I do, I may not have all the facts at hand, there are others who support her view, etc. You go back and rate the original stressor statement and find that it's no longer the source of your pain.
What I find remarkable about this exercise is that the process instantly diffuses my stress. If forces me to see the other side and by doing so I realize that what I thought about I situation may not be true after all. It takes a bit of practice and it's easy to turn it into an exercise in making excuses. But if you keep it constructive and dig deep to the source, it's an effective way at challenging your negative beliefs and essentially removing them.