Self sabotage is a habit. Thinking pessismistically is a habit. Being insecure is a habit of mind. Doubting your judgement is a symptom of low self esteem. If you desire to change your mental paradigm, you must first root out the origins of your insecurity. Your feelings of self doubt are not intrinsic to your personality. These are attitudes you developed about yourself growing up. You can ask yourself if you were teased as a child? Or taught that your feelings did not matter? Did you feel out of touch with your environment? Did you find socializing too painfull? Was you a nerd? A drop out? Or a brilliant but lonely student? These are simply factors the answers to which provide insight how, when and why, you became insecure. Insecurity is a frame of mind. Risk takers tend to exaggerate their competence. Those who are meek, mild, and passive by nature, tend to devalue themselves. It may feel dangerous, arrogant, or out of character to behave in a competent manner. However, my suggestion to those who tend to sabotage themselves, is to try a new strategy. Once this new experience becomes accepted and incorporated into your self image, new habits will emerge.