Age differences in responses to framed health messages—which can influence judgments and decisions—are critical to understand yet relatively unexplored. Age-related emotional shifts toward positivity would be expected to differentially impact the affective responses of older and younger adults to framed messages. In this study, we measured the subjective and physiological affective responses of older and younger adults to gain- and loss-framed exercise promotion messages. Relative to older adults, younger adults exhibited greater negative reactivity to loss-framed health messages. These results suggest that health message framing does matter, but it depends on the age of the message recipient.