Bandura explains that the most effective way of developing a strong sense of self-efficacy is through "mastery experiences". Successfully completing a task strengthens our sense of self-efficacy. However, failing to adequately complete a challenge can undermine and weaken self-efficacy. "Social modeling" is the act of witnessing other people successfully completing a task. The second influential way of creating and strengthening self-efficacy beliefs is through "vicarious experiences" provided by social models. Bandura suggests that watching people similar to oneself succeed with sustained effort raises the observers' beliefs that they also have the ability to master similar activities to succeed.