Expressing yourself assertively means communicating your feelings directly and respectfully. Some people have difficulty being assertive in certain situations or with certain people (for example, asking the boss for a raise). Others have difficulty being assertive in nearly all situations. Some people who have difficulty with assertiveness find themselves saying "yes" when they really want to say "no," discounting their own needs and prioritizing those of others, and doing what others expect and want instead of what they themselves would prefer. These individuals are passive instead of assertive. Others who have difficulty with assertiveness tend to be aggressive and demanding rather than assertive, and still others use manipulative or indirect strategies rather than expressing their wishes directly and assertively. None of these unassertive styles is usually effective or satisfying, and all can contribute to anxiety, resentment, depression, and difficulties in relationships and work.

Cognitive behavior therapy helps the unassertive person identify and pinpoint his difficulties with assertiveness, identify and change beliefs (such as, "If I speak up, he will get angry and yell at me") that contribute to assertiveness, and learn and practice skills for expressing oneself appropriately and assertively.