A big part of self-awareness relates to how you behave in life. Certain behaviors lead in certain direction and a certain type of results. Think about the person who lies, cheats and steals his way to success. He (or she) may have amazing wealth or power, but there will always be something missing because they got there practicing negative behaviors.
The key in life is to be nice so that you can experience the peace of mind that comes from knowing you behaved in a way that was kind, honorable and ethical. Being nice doesn't mean being weak, it refers to conducting yourself in ways that encourage kindness and build harmony. Ultimately, being nice helps you enjoy life more because you don't have to worry about all the repercussions that come from behaving negatively.