The mature person realizes that life is fraught with problems and uses the power within them to mitigate the difficulty without making it more complex by feeling anger. In order to get things done, we are told to visualize. Picture in your mind how you are going to attack the problem. It stands to reason that if you always think in the negative, your outcomes will probably all come true and you will fail. Visualize in the positive only.
Negative thoughts kill ambition.
Become the master of yourself. Believe in your own possibilities. You only have a weakness if you think you do. Concentrate on the awareness of your ever increasing ability. Harboring any negativity means that energy has to be stored somewhere inside you.