Engagement in cognitively demanding everyday activities has been shown to benefit cognitive health in later life. We investigated the factors that influence engagement, with specific interest in determining the extent to which the costs of engaging cognitive resources are associated with intrinsic motivation and, ultimately, participation in everyday activities. Older adults (N = 153) aged from 65 to 81 years completed a challenging cognitive task, with the costs of cognitive engagement—operationalized as the effort required to maintain performance—assessed using systolic blood pressure responses (SBP-R). We also assessed participation in everyday activities using both 2-year retrospective reports and five daily reports over a 5-week period. Structural models revealed that lower levels of costs were associated with more positive attitudes about aging, which in turn were associated with higher levels of intrinsic motivation. Motivation was subsequently predictive of everyday activity engagement, with the effect being specific to those activities thought to place demands on cognitive resources. The measure of engagement had minimal impact on the nature of the observed effects, suggesting that the retrospective and weekly assessments were tapping into similar constructs. Taken together, the results are consistent with expectations derived from Selective Engagement Theory (Hess, 2014), which argues that engagement in demanding activities is related to the cost associated with such engagement, which in turn leads to selective participation through changes in motivation.