In Reply We thank Aguiar and colleagues for their letter and very much agree that “Although it is still premature to provide empirically supported step-based recommendations, it is important to consider the implications of [available] findings for public health, physical activity guideline development, and individual goal setting.” It is encouraging to note a congruence between our findings of decreasing mortality rates with more steps taken a day until approximately 7500 steps/d when rates leveled1 and findings of a study by Tudor-Locke and colleagues2 showing approximately 7000 to 8000 steps/d being equivalent to meeting physical activity guidelines. Our study addressed all-cause mortality (and not other health outcomes) among older women (and not other age groups); thus, additional data are needed to obtain a full picture of the associations between physical activity and health. These data are forthcoming: in recent years, an exciting development in the field of physical activity research is the emergence of several prospective cohort studies that collect detailed information on physical activity using devices instead of relying on self-reports, as was traditionally completed. These studies are able to provide novel information, such as that related to light-intensity physical activity, which is not well reported, to inform future physical activity guidelines.3