The mind gets conditioned by the thoughts we have everyday, so much so that it becomes ingrained as a habit. Hence it is important to cultivate wholesome thoughts and not unwholesome thoughts as they will mould our character. Very few people are aware of the ability of the mind to generate thought forms. These thought forms are energy beings with consciousness. This subject is taught in Theosophy and Pranic Psychotherapy. Thought forms, whether positive or negative, can affect oneself and other people. Therefore, it is important to generate good thoughts to benefit oneself and others. Do not sabotage yourself by thinking negative of oneself, or unintentionally hurt your loved ones with negative thoughts about them. Remember that the mind is the forerunner of all things, for thoughts will lead to feelings & emotions which will have subsequent impact on speech and action. That is generating karma as intention is involved.
