Self-efficacy refers to one's belief that they can succeed with a given behavior in a particular context. It is a concept largely popularized by Albert Bandura as a key component of social cognitive theory.
Increasing self-efficacy can be an effective tactic for mediating a person's intention to perform a behavior and their actual performance. Typically, this entails positive feedback around elements of the behavior they've performed correctly, information about others who have succeeded (i.e. viarious experience), or other information aimed to improve a person's belief they can be successful with a behavior.
A notable perspective on self-efficacy comes from the Health Action Process Approach, which distinguishes self-efficacy related to initial performance vs. maintenance and other instances of performing the behavior.