You can't expect to prevent negative feelings altogether. And you can't expect to experience positive feelings all the time. The Law of Emotional Choice directs us to acknowledge our feelings but also to refuse to get stuck in the negative ones.
If I feel depressed I will sing. If I feel sad I will laugh. If I feel ill I will double my labor. If I feel fear I will plunge ahead. If I feel inferior I will wear new garments. If I feel uncertain I will raise my voice. If I feel poverty I will think of wealth to come. If I feel incompetent I will think of past success. If I feel insignificant I will remember my goals. Today I will be the master of my emotions.