Over-reliance on extrinsic rewards, like using a Fitbit to track exercise, can lead to misery and a loss of enjoyment in the activity itself.

“the fiction writer David sideras has this wonderful uh article called the Fitbit life where he talks about how he wanted to get fit it's in intrinsic reward of you know exercising more and he got the Fitbit and then it was all about the Fitbit he would set the level higher and set the level higher and he himself was miserable and no longer enjoying running to the point that like at some point he just would walk around you know shaking his arm just to get up to those final steps right”