Brief intervention can range from 5 minutes to 2 hours and involves an informal assessment of the client's situation, thoughts, and developing a strategy for change. It is based on harm minimization principles and can be used to discuss personal health, substance use, mental health issues, and their effects on family. The most important factor is developing a relationship with the client. Brief intervention may not be appropriate if the client is resistant, intoxicated, unwell, or has complex chronic issues. In those cases, referral or postponing may be necessary. Brief intervention can help clients develop a sense of power, identity, purpose, self-acceptance, and management of social issues.