Applying Nolen-Hoeksema and Watkins's (2011) transdiagnostic risk factor heuristic to our work on positive activities (i.e., practices that characterize naturally happy people, like expressing gratitude and practicing generosity), we propose that such activities may serve as protective factors that mitigate proximal risk factors both directly and by intervening with the mechanisms that give rise to them. First, we discuss theoretical and empirical support for the importance of well-being and the mechanisms that explain how positive activities promote well-being (by boosting positive emotions, positive thoughts, positive behaviors, and need satisfaction; Lyubomirsky & Layous, 2013). Second, we outline examples of how positive activities can mitigate two particular proximal risk factors (rumination and loneliness) and counteract environmental triggers (i.e., moderators) that might amplify them (e.g., through adaptive coping). Third, we argue that positive activities can be taught to youth to instill positive patterns of emotions, thoughts, and behaviors that may serve as protective factors over the course of their lifetimes. Lastly, we propose that certain positive activities might be particularly well-suited to certain individuals and to specific risk factors.