This article was originally published on December 28, 2015.Fitness trackers are supposed to motivate us to get out and there do fitness things. But for some of us, being monitored by those little wristbands can make exercise less enjoyable. And a new study could help explain why.For the study, to be published in an upcoming issue of the Journal of Consumer Research, the researchers performed six experiments. In one, 95 participants recorded their thoughts while walking for a day. Half of them were told to keep track of their steps using pedometers while the other half wore pedometers, but couldn't check their steps — only the researchers knew how many steps they'd taken. Results showed that those participants who could see their steps ended up walking farther, but reported enjoying it less than those who didn't know how far they'd gone.This brings up an important concept in the field of motivation psychology: extrinsic vs. intrinsic rewards . Getting points or badges for walking a certain distance is an external — "extrinsic" — reward. But if you already enjoy walking because you enjoy having that time to yourself or exploring new parts of your city, or even just the feeling of being active, it's "intrinsically" rewarding. And if you suddenly start receiving extrinsic rewards for doing it, they may take away from those intrinsic rewards.In a classic experiment that looked at this idea, researchers looked at kids who loved drawing. When kids were explicitly told they would receive a reward for drawing (a fancy certificate with a gold ribbon), they actually spent less time drawing in the next few school days than those who didn't get a reward and those who were surprised with a reward. Researchers took a thing the kids loved and made them less interested in it by giving them a reward for doing it.So the new study suggests that if you're already a fan of exercising, then running for points probably won't make you enjoy it more — and it could even make you enjoy it less. But if you're having a hard time getting those sneakers on and actually running in them, a tracker might be just the thing you need to get you moving.