Conclusions
Physical activity is a critical determinant of health and well-being. This research suggests that it is not only our actual physical activity behavior that matters but also our mindsets about the adequacy and health consequences of our physical activity. Moreover, it shows that wearable fitness trackers can shape these mindsets. These insights may be used to support the design of wearable trackers and other health technologies that more effectively boost users’ health and well-being. In addition, health psychology research and public health policy may design more successful public health interventions by more deliberately––and more effectively––harnessing the power of mindsets.This research was supported in part by a grant from the National Center for Complementary and Integrative Health (grant 1DP2AT009511-01), the Stanford Catalyst for Collaborative Solutions Research Grant, and the Stanford Center for Digital Health 2017 Apple Watch Seed Research Grant. The authors thank A Martin, J Pfeffer, and the Stanford Mind and Body Lab (including D Barbiani) and Design and Process of Experimental Research Lab for their contributions to this research or comments on this paper. OHZ is now affiliated with the European Central Bank. The views expressed in this paper are the author's own and do not necessarily reflect those of the Eurosystem or the ECB. EM is now affiliated with the School of Engineering, Dartmouth College.Conflicts of Interest: None declared.Supplemental methods, materials, and results.CONSORT-eHEALTH checklist (V 1.6.1).