CBT is based on the concept that our thoughts affect our behaviors, which in turn, affect our emotions. This cause and affect loop can work in any direction.
For example, if your boss gives you some feedback, you might tell yourself that you are a COMPLETE loser, and you ALWAYS do EVERYTHING wrong. These thoughts will affect your emotions and you might become depressed and sad and angry. In reaction to these feelings, you might go home and “self-medicate” with your drug of choice: excessive television, alcohol, food, etc. This behavior might in turn make you become critical of yourself, and reinforce the idea that you ARE a loser. Then you might go back to work and mess up, because you are thinking poorly of yourself and hung over, and the whole cycle might begin again.
CBT helps you to identify “irrational” thoughts like the ones listed above. Pretty much anything you think that involves an “absolute” is irrational on some level (always, never, complete, everyone, perfect, etc.). Many of these thoughts were instilled in our minds when we were little and needed black and white rules.
For example, it is appropriate for a child to never talk with strangers. If an adult continues to follow this rule, life will be very limited.
Once you can identify your irrational thoughts, you have an opportunity to correct them, and stop the whole sequence.
You also make changes on the behavioral/action level. Instead of self-medicating, you can learn positive and productive ways to self-soothe, and then problem solve. For example, you might talk to a friend, or go for a walk, or work on a hobby, and then address the feedback from your boss in a constructive way.
CBT frequently involves doing “homework,” or actively making different behavioral choices and learning different habits of thinking.
You are coming to therapy to improve your life. This will require work on your part to make it happen, but the rewards are worth it!