I had a friend ask me, why are you always optimistic? I laughed, telling her that I have my moments, as we all do, but answered with a question of my own; would you rather me pessimistic and negative?
There are a couple points to our interaction; 1) If I were mostly pessimistic about life, who the hell would want to hang out with me? The law of attractions would cause me to endure some pretty miserable experiences going forward, which would continue the cycle of anger. Being positive allows me to see the brighter side of life and how grateful I am that good things and people enter my life. As someone who was very miserable, I can say from experience that the law of attractions is truth.
2) Regardless if bad things do happen to us, I gave up a long time ago getting angry over situations and people because we have zero control over them. The only things we control are our behavior and reactions to those that do right and wrong by/to us. A way to turn any bad situation around is to look at it as a learning lesson and take that lesson forward in life when a similar circumstance approaches.
We have our ups and downs, while it's easy to get caught up in our anger, we need to realize that it's a vampire that sucks the energy out of us. Pessimism is the byproduct of anger, therefore it slowly drains us and how we respond to opportunities. I learned that having optimism keeps us full of vitality, ready to take on life.