Table 2.

Interview guide and example questions.

Interview			Example questions
First interview
	Interview topics
		Icebreaker	Can you describe how you use your tracker on a typical day?
		General use	What features do you use the most and least and why? Did you set a goal for yourself when using the wearable activity tracker? How do you feel when you don’t reach your goals?
		Habit formation	Tell me the story of when you started using your tracker. What made you decide to start using one? Why have you continued to use your tracker for so long? What got you in the habit of using your tracker? Are there times of the day you use or notice your activity tracker more than other times of the day? What makes it difficult to use the activity tracker on those days? How do you deal with the difficulties? If a friend wanted to use an activity tracker every day for a year, what are the three main pieces of advice you would tell your friend?
		Tracker data usage	How often do you check your tracker data? Do you share your tracker data? How do you use the data provided by the tracker?
Second interview
	Interview topics
		Photo diary opening question	What physical activity were you doing when you took this photo?
		Context	Where were you when you took this photo?
		Benefits of wearable activity trackers	How did you feel physically while doing this activity? How do you see the wearable activity tracker contributed to your physical health? Were you with anyone when you used the activity trackers? How do you see the wearable activity track contributed to your social life?
		Successful strategies of long-term use	Please explain to us the successful strategies you employed to continue using the wearable activity tracker, which are captured in these photos.