The use of mobile and wireless technologies has been rapidly increasing worldwide and sparked a growth in the use of these technologies to support the achievement of health objectives (i.e., mHealth). This dissertation aims to test the effect of an mHealth intervention using mobile apps for promoting healthy lifestyle behavior change among college students. It takes an “active ingredient” perspective that examines the utility of a single strategy in mHealth interventions. The strategy is called episodic future thinking (EFT), the ability to project oneself into the future to pre-experience future events. Drawing on future thinking, intertemporal choice, and construal level theory, this dissertation proposes that engaging in EFT (vs. episodic recent thinking, ERT) could help individuals make better health-related choices in their everyday lives in terms of taking sufficient sleep or physical activity. Through a two-week mHealth intervention using the health apps SleepCycle and NikeTrainingClub, this dissertation examines the effect of EFT on two lifestyle-related behaviors, i.e., sleep and physical activity participation, and explores the psychological mechanism underlying EFT’s effect. The findings suggest that EFT could be a useful strategy incorporated into mHealth interventions to increase intentions for health behavior change and to promote actual behavior change among college students. However, it might have contradictory effects when applied to different types of behavior. Specific to the current study, EFT was effective in promoting physical activity as recorded through the health app NikeTrainingClub. However, EFT had negative effect when applied to the sleep behavior. The reasons why this was the case are explained and theoretical and practical implications for EFT research and mHealth interventions are discussed. In general, the findings complement and extend previous research on EFT and mHealth interventions and emphasize the importance of context (including the context of mobile technologies) in mHealth intervention research.