Our objective was to highlight age-related differences in subjective affect and its variations between adolescence and old age in an ecological environment, running generalized additive models to look for nonlinear relationships between age and affect. The originality of this research lay in its consideration of the levels of both affective valence and affect activation. Over a 2-week period, 209 participants aged 13–80 years completed a daily survey based on the experience sampling method, each providing an average of 60 observations. Results revealed 1) two nonlinear patterns of age-related differences in affective valence during the first (declines in deactivated negative affect and deactivated positive affect) and second (continuing decline in deactivated negative affect and increase in deactivated positive affect) halves of adulthood, and 2) one linear pattern of age-related differences in affect variation in the shape of a two-step reduction in the amplitude of variation, with a more marked reduction in the second half of adulthood. Results are discussed in the light of age differences in motivation and affect regulation expertise.