Table 1.

Topics and guiding questions of the interview

Topic	Interview guide question
Spontaneous impression	– What comes to your mind when you think of the #LIFEGOALS app?
Feasibility	– How was it to use the app? – Why was it (not) easy to use? – What did you (not) enjoy? – What did you think about the looks of the app?
Mechanisms of action	– With what has the app helped you? – How/in what way did the app help you with that? / Why didn’t the app help with anything?
Used as intended?	– Can you tell us some more about [component X]?a – How have you used [component X]?a
Context and usage	– When and where have you used the app? – What has (de)motivated you to use the app? – How did others (peers, family, teacher) feel about the app? What influence did this have on you?

^a Asked for each component of the app separately