A recent study found that activity trackers can actually de-motivate teenagers:
The problem with the monitors seemed to be that they had left the teenagers feeling pressure and with little control over their activities, as well as self-conscious about their physical abilities, said Charlotte Kerner, a lecturer in youth sport and physical education at Brunel University London, who led the study. The result was frustration, self-reproach — and less, not more, movement.
“You can’t just give a child a Fitbit for Christmas and expect them to be active,” Kerner said. “They will need educating on how best to negotiate the features.” Nudge them to set realistic step counts and other fitness goals, she says, and to consider whether they want to share their results with friends. For many young people, fitness may be better achieved in private.
I would be interested in why this happens, and how prevalent it is in adults. For some adults, like me, having an activity tracker is really motivating. I've arranged my life in part to make sure I get lots of steps, often more than 4,500 by the time I've gotten to work in the morning (or 9,000 if I walk the whole way).
Teenagers, though, really resent being told what to do. I wonder how this study could be altered to reduce that part of adolescent psychology.
Update: I just discovered that, when I hit 10,611 steps today, I'll have 15 million lifetime steps on Fitbit. Cool.