Social pressure, family, peers and society as a whole can be a huge force in determining people's behavior and shaping the goals and ideals people strive for. There can be a great internal struggle for many individuals reconciling "being" what they perceive others want them to be with being able to express themselves as they truly are.
There are many structures that reinforce conformity such as conditioning through fear, shame and guilt. Religion is a particularly poignant example.
To what extent does suppressing healthy behaviour that is inconsistent with external standards cause psychological difficulties?