Many people don't think about what they think about. That sounds confusing, I know, but let me explain. What I mean is that most people do not know what they are thinking most of the time. They are unaware of their thoughts, and unaware of the effect that their thoughts have on them and their environment.
For much of my life, I was the same way. I did not understand how what I was thinking affected me. But through the help of friends, and through reading books like "The Book of Secrets" by Deepak Chopra, and "The Power of Now" by Eckhart Tolle, and through my studies of Neuro-Linguistic Programming, I began to realize the power of my thoughts. What thoughts are:
Whenever we sense something consciously, we represent it to ourselves with a thought (or three). The thought turns our raw sense data into a bit of language that floats around in our head. In that sense, we use our thoughts to label things.
The thought-labels we create are based on understandings we gained in the past, on our own personal definitions of words, on our own personal sensory information, on our cultural teachings and programming, and on our emotional state at the time the thought enters our mind. Because of this, our thought-labels for things are entirely subjective. We only know that leaves are green because we have been taught to associate the word "green" with the way a leaf appears to our eyes.
One of the greatest steps in life that leads to happiness is to have a flexible mind. I don't need to say anything to prove this, because you've experienced it yourself. The most unhappy people are the ones who are the most stuck in their ways.
Some of the most negative people I've ever been around were people who had a mind that went in a constant self-defeating loop. They always speak negatively of their circumstances, the people around them, themselves, everything. They say the same things over and over again. They also point the finger constantly at anything but themselves. Then they wonder why they are unhappy.
I was the same way in the past. My thoughts revolved constantly around the things I didn't want, and because that was where my thoughts were focused, that was always what I got. The good thing is that I was able to catch it before it got further along, and before I became totally unaware of my thought patterns. Now, every day I try to think more and more positively.
This is not simply covering up what you feel. What you feel is really just a deeper level of what you think. So if you feel bad, then on that deeper level you are thinking negatively. Many times though, people do not have or do not seem to have immediate control over what they feel. As you study these things more, you'll find that it is possible to control your feelings to the extent that you are willing to, but that's another topic for another time.
Something that many of the modern-day sages agree on is that what you focus on is what you get. Thoughts become things. To get something other than what you have now, you must change your focus. A great movie to watch on this topic is "The Secret". Following is a diagram of the thought-thing process.
Another interesting thing to note about this process is that it is cyclic in nature. In other words, negative thoughts beget negative emotions, which tend to cause negative actions (or inaction) which brings about negative life-circumstances, which naturally gives rise to more negative thoughts, etc.
The good news is that the same is true for the positive side. The cycle works both ways. It is a tool provided us by the universe, how we use it is up to us.
Here is another way to look at the cycle of the creation process, your internal state is a pond. Sometimes--like when you're in a deep, dreamless sleep--it is a tranquil and still pond, cool and clear. In times of emotional trauma and fear, it is a raging whirlpool of negativity and emotion. Your conscious thoughts are like the surface of the pond, and your emotions are like the depths of it. The currents that run beneath the surface also affect the surface. And if you stir the surface long enough, it affects the depths.
Typically what happens is this: someone starts watching their thought life and thinking more positive thoughts, but they still feel bad. What is happening is simply the initial process of internal change. There is a deep, strong current going one way below the surface, and they are trying to change the direction of it by stirring the surface in a different direction.
This may seem an impossible task, but it is not. It simply takes some time, and some committment. Eventually, the constant stirring of positive thoughts on the surface will filter down into the emotions, creating slow change in the current beneath the surface. When you stir long enough, the current below will slow, then stop, and then reverse its flow. Then you keep stirring, and keep stirring, and soon you have built momentum in the other direction. Now your emotions are flowing positively!
Now you find yourself not only thinking good thoughts, but also feeling good. And when a negative thought enters your mind, it finds its way out much quicker, with much less impact, because it can't stand up to the force of your positive momentum.
Why should you do this? Why try to watch your thoughts? Why try to change them? Well, to put it simply, do you want to be happy? How can you possibly be happy while you are just thinking any random old thing that jumps into your head? Can you be happy while your mind is run by negative, blaming, accusing, nasty thoughts?
Want to be happy? Change your thinking.
Please note that the first step towards changing your thinking is accepting your thought life where it is right now. This may seem contradictory, but it is not. If you feel guilty for your thoughts, you will never stop feeling guilty, and that will defeat the purpose of watching your thoughts.
What you must say is this, "Right now, I am thinking negative thoughts, placing mental blame on others, etc. And that is all okay. I think this way because before this I did not know I had a choice. I accept my negative thoughts, and now I turn my mind to positive thoughts."