All of us view everything through our prevailing mental attitude. If our thoughts are positive, that is fine, but if they are negative, our lives and circumstances will probably mirror these thoughts. We all have negative thoughts every now and then. This is normal behavior as we might have gone through some unpleasant experiences in our lives. But too many negative thoughts are bad and can be self-destructive.
Negative thinking appears to be more prevalent than positive thinking.
Positive thinking requires some effort, whereas negative thinking comes easily and uninvited. This has much to do with education and the environment one has been living in. Many teenagers experience and develop negative thoughts--either because they are unhappy with school or their life is not going the way they thought it would, or because of peer pressure or failures. Negative thoughts such as greed, anger and hatred are like viruses. If you give them any attention, they will start to breed and become increasingly difficult to get rid of. To have a positive impact on your life, negative thoughts should not be left unattended. They are a thousand times more addictive then drugs. Over time, they overwhelm you so much that you cannot distinguish thoughts as being separate from you.

Decide that from today -from this very moment -you are leaving negative thinking behind, and starting positive thinking and behavior.