Habits are automatic behavioural responses to environmental cues, thought to develop through repetition of behaviour in consistent contexts. When habit is strong, deliberate intentions have been shown to have a reduced influence on behaviour. The habit concept may provide a mechanism for establishing new behaviours, and so healthy habit formation is a desired outcome for many interventions. Habits also however represent a potential challenge for changing ingrained unhealthy behaviours, which may be resistant to motivational shifts. This review aims to provide intervention developers with tools to help establish target behaviours as habits based on theoretical and empirical insights. We discuss evidence-based techniques for forming new healthy habits and breaking existing unhealthy habits. To promote habit-formation we focus on strategies to initiate a new behaviour, support context-dependent repetition of this behaviour, and facilitate the development of automaticity. We discuss techniques for disrupting existing unwanted habits, which relate to restructuring the personal environment and enabling alternative responses to situational cues.