The newest addition to the list of iPhone-based nudges is NudgerSize, developed by Keystone Insights, LLC, that seeks to get people into exercising and also calibrating how often and how long we exercise.
The "Nudge-Your-Size-Back" iPhone application uses multiple voice reminders or pop-up messages or sound alerts to encourage users to exercise and increase their exercise productivity. It even has customizable voice nudges - friendly, supportive, humorous or aggressive - depending upon personal needs.
A recent WSJ article had pointed to a Stanford University study of 218 people, which found that "small amounts of social support, ranging from friends who encourage each other by email to occasional meetings with a fitness counselor" can help people break out of physical inactivity. The study had divided people into three groups - first and second received periodic calls from a trained health educator and an automated computer system respectively, while the third control group received only initial health education tips but no follow-up calls.
It found that after 12 months, participants receiving calls from a live person were exercising an average of about 178 minutes a week, a jump of 78%. Exercise levels for the group receiving computerized calls doubled to 157 minutes a week. But for the control group of participants, who received no phone calls, exercise levels rose up only 28% to 118 minutes a week.
Update 1 (23/2/2011)
Alan M Garber and Jeremy D Goldhaber-Fieber have this post in Vox about the behavioural psychology way to get people to exercise more.