Decreasing excessive media usage while increasing physical activity: a single-subject research study.

Heo et al. (2008) worked with one teen who spent most free time on screens. They set up a token board. Each minute of exercise earned a token. Tokens bought minutes of media time.

The team tracked exercise minutes and screen minutes every day for several weeks. They also checked if the gains lasted five weeks later and again after one year.

Exercise time shot up. Screen time dropped. The teen kept the new balance five weeks after tokens stopped.

One year later the teen was still active and had even added new workouts. The media-for-move swap stuck.

McCullen et al. (2025) used a similar idea with adults but gave money instead of media. Steps rose fast, yet fell once the cash ended. The teen in H et al. kept going without tokens, showing media itself can lock in the habit.

Rotta et al. (2022) and Li et al. (2019) stretched the token plan to adults with intellectual or developmental disabilities. They added choice and lottery prizes. All studies show tokens boost steps, but H et al. is the only one with a one-year follow-up that kept improving.

Erath et al. (2022) tried remote cash for office workers. Only four of six increased walking. The teen case had a clearer win, perhaps because media time is a stronger reinforcer for teens than small money is for adults.

You can turn screen time into a reinforcer instead of fighting it. Let clients earn minutes of games or social media by logging minutes of movement. Start with a one-to-one swap, then thin the ratio. Track for at least a month to see if the new habit sticks. This single-case design gives you a quick template to test with other teens who are glued to their phones.