It is important for us to reflect on how we got to where we are today and how we can change in the future. Let me illustrate how our thoughts and feelings can change the quality and direction of our life. Unfortunately, if I use a negative story, it might be easier for us to get the point, as we are all personally well versed in such things. So, say that we have an unpleasant exchange with a coworker one day. It isn’t significant, but we keep thinking about it and feeling dislike for that person. Soon, whatever this person says or does, whether it actually touches us or not, annoys us. Every exchange, whether smiling or frowning, triggers harsh feelings in us toward them. After some time, even seeing this person’s e-mail in our inbox can make our heart skip a beat. Then, merely thinking about this person makes us feel frustrated and miserable. It doesn't matter if they are miles away. It consumes us. We constantly bring their annoying demeanor vividly to mind and keep hearing their irritating voice loudly—as if they were right in our face. Obviously, real harmful actions and harsh words will fly back and forth when you actually meet. We may force ourselves to smile, but whatever we say or do relating to this person will become harmful. Our forced nice gestures won’t charm anyone, as they came from an agitated state of mind. This illustration is probably familiar to many of us.
But it is ourselves that we harm most. We accumulate poisonous emotions that hurt the elements and energy systems of our body and can lead to sickness and disease.
Source: The Heart of Unconditional Love