This paper provides evidence that scores on simple, low-stakes tests are associated with future economic success because the scores also reflect test takers' personality traits associated with their level of intrinsic motivation. To establish this, I use the coding speed test that was administered without incentives to participants in the National Longitudinal Survey of Youth (NLSY). I show that, controlling for cognitive ability, the coding speed scores are correlated with future earnings of male NLSY participants. I provide evidence that the coding speed scores relate to intrinsic motivation. I show that the scores of the highly motivated, though less educated, group (potential recruits to the U.S. military), are higher than the NLSY participants' scores. I use controlled experiments to show directly that intrinsic motivation is an important component of the unincentivized coding speed scores and that it relates to test takers' personality traits.