Table 1.

Overview of the self-regulation techniques implemented in the website.

Self-regulation technique	Implementation mode
Providing information on the consequences of behavior, in general	During session 1, users have the option of taking a quiz. The quiz contains questions regarding the benefits of the chosen health behavior (ie, increasing physical activity or reducing sedentary behavior). Each answer is followed by a clear explanation.
Exploring social support	During session 1, users can read more information about how they can obtain social support from their partner, friends, family, or colleagues.
Providing feedback on performance	During session 1, users complete a short questionnaire regarding their current levels of physical activity or sedentary behavior. Thereafter, they can see for how much time they are physically active or sedentary and in which domains (eg, transport or leisure time).
Action planning	In each session, users have the option to create their own goals to increase their physical activity or decrease their sedentary behavior. By answering different questions, the goals are made as specific as possible (eg, “On Monday and Wednesday morning I will walk 10 minutes in the neighbourhood”).
Barrier identification/problem solving	In each session, users are prompted to think about possible barriers regarding their plans and search for potential solutions (eg, “I might forget my plan to take a walk in the evening, so I will stick a note on the fridge”).
Prompting self-monitoring of behavior	In each session, the website encourages users to monitor their behavior change and presents options to do so.
Prompting review of behavioral goals	During each follow-up session, users are asked to review the extent to which the goals set in the previous session were achieved.