This data viz depicts the within-person association between morning positive affect (along the invisible x-axis) and later-day smoking urges (along the invisible y-axis), where each grey line depicts the association for an individual participant using 5x/day ecological momentary assessment data during 4 weeks of a scheduled quit attempt. The yellow line shows that the average within-person association is slightly negative such that on mornings when individuals’ positive affect is higher than usual in the morning, their smoking urges later in the day tend to be lower than usual. The green and blue lines highlight the extent of heterogeneity across participants showing that for some people this is a strong negative association (e.g., green line), and for others this is a strong positive association (eg., blue line). My goal is to use this to show how an average within-person association can be used as “warm-start” information in an intervention as well as the need for personalization methods to tailor interventions to the unique needs of individual people. For example, perhaps a different intervention approach is needed for individuals who have strong positive coupling vs. strong negative coupling between their morning positive affect and later-day smoking urges.