Interventions for noncommunicable diseases (NCDSs) often require changing behaviors. In this regard, habitual behaviors (i.e., habits) are positively evaluated to foster behavioral changes. Forming habits is challenging but can be supported digitally until the habit is formed. This paper reviews the requirements of forming habits and uses a content analysis to investigate how these requirements are implemented in habit apps. Based on the results, design principles to digitally support habit formation are discussed for digital therapeutics. In contrast to conventional apps, digital therapeutics have a definite medical purpose and can be prescribed for the time it needs for a habit to form. The analysis results reveal that conventional apps try to bind the user and ignore the state where the habit needs to be strengthened by decreasing technology use. In this regard, digital therapeutics reveal great potential in supporting the formation of habits to prevent and treat NCDs.