Do you berate yourself for things you do or say? Are you afraid to make a mistake? Relax. Chances are you are not a bad person, and most likely, you do at least one thing well. Perhaps it is time for a self-esteem tune-up.

Yale University researchers found that a "bad hair day" can be hazardous to your mental health. If something as insignificant as an out-of-control coif can "diminish your self-esteem and inspire feelings of incompetence, self-doubt, and even self-hatred," what might happen if you were late for work? Or had a fight with your boss?

"How we feel about ourselves crucially affects virtually every aspect of our experience...from the way we function at work, in love, in sex, to the way we operate as parents, to how high in life we are likely to rise. The dramas of our lives are the reflections of our most private visions of ourselves," says Nathaniel Branden, a renowned psychotherapist and author, viewed by many as "the father of modern-day self-esteem psychology."

According to Branden, self-esteem has two components: a feeling of personal competence and a feeling of personal worth, reflecting both your implicit judgment of your ability to cope with life's challenges and your belief that your interests, rights, and needs are important. Healthy self-esteem comes from realistically appraising your capabilities, striving to enhance these capabilities, and compassionately accepting your limitations and flaws. Living consciously thinking independently, being self-aware, being honest with yourself, having an active orientation, taking risks, and respecting reality, says Branden, is the foundation of good self-esteem.