Exercise is routinely recommended because of its benefits for physical, cognitive, and mental health. It is especially beneficial for older adults due to its potential buffering effects against Alzheimer's disease and related dementias (Luck et al., 2014). However, little is known about how to best encourage older adults to exercise. Based on behavior change theory, different intrapersonal and interpersonal motivational factors are likely to be relevant during the contemplation, action, and maintenance stages of behavior change. Generally, as a result of motivational shifts toward prioritizing positivity and socially meaningful goals with advancing age (Carstensen, 2006), socioemotional aspects of decision making may become more salient and influential for older adults (Mikels et al., 2015; Peter et al., 2011). Our previous work has demonstrated that positive affect (Mikels et al., 2020) and social goals (Steltenpohl et al., 2019) play a critical role in older adults' motivation to exercise, but these two lines of research have not been integrated to date. Recent work indicates that positive affect is particularly beneficial for health when shared in social connections (Fredrickson, 2016; Major et al., 2018), and the proposed work will, for the first time, examine how shared interpersonal positivity may impact exercise decision making and behavior, especially during the contemplation and action/maintenance stages of behavior change.

But who are the older adults that benefit the most from exercise in terms of physical, cognitive, and mental health (and should be hence be targeted with messages)? Not all older adults reap the benefits of exercise (Sparks, 2014) and, conversely, sedentary older adults have the most to gain. Overall, the current proposed research program is innovative in its (a) translational application of insights from affective, cognitive, and aging theory and research to understand the antecedents and outcomes of exercise decision making in younger and older adults, (b) conceptualization of both the social and emotional aspects of decision making, (c) development of novel methods for health messaging that incorporate social influences, and (d) novel assessments of the exercise-health link.

Our specific aims are:

Aim 1: To understand how social and emotional processes contribute to age differences in health-related decision making. Message framing is an effective means of promoting behavior change, with loss-framing emphasizing the negative consequences of not engaging in a behavior, and gain-framing emphasizing the benefits of engaging in a behavior (Rothman & Salovey, 1997). Although affect has been examined in messaging, intrapersonal vs. interpersonal benefits and consequences as well as the role of shared positive affect have not. We propose that interpersonal vs. intrapersonal framing will differentially influence positivity toward exercise for sedentary and active older vs. younger adults. Experiment 1 (laboratory-based) will examine affective reactions, evaluations, and behavioral intentions in response to framed messages. To better understand the social processes involved in exercise decisions, Experiment 2 (field-based) will examine the same outcomes of Experiment 1 when people exercise alone or with another person, with a focus on whether shared positive affect is more motivating for older vs. younger adults when engaged in physical activity.

Aim 2: To determine how social and emotional factors impact exercise engagement, adherence, and maintenance. Experiments 3, 4A, and 4B will examine whether intrapersonal vs. interpersonal factors disproportionately impact exercise intentions and behavior. In Experiment 3, intrapersonal vs. interpersonal framing will be applied to recruit and enroll younger and older adults into an exercise program. In Experiment 4A, we will examine whether social and emotional factors - including shared positive affect - influence the engagement and adherence of older adults enrolled in an evidence-based fitness program, Fit & Strong! (Hughes et al., 2006). In Experiment 4B, we will measure social and emotional influences on continued physical activity one year after the program ends. In these latter two experiments, we will measure actual behavioral outcomes including objective measures of physical activity and attendance, as well as shared positive affect, cognitive function, and well-being.

Aim 3: To extend the established benefits of Fit & Strong! for older adults into physiological and cognitive domains. It is well-established that exercise improves physical, mental, and cognitive health (Hillman et al., 2008; Hughes et al., 2006). We will expand the documented benefits of a particular exercise intervention tailored for older adults, Fit & Strong!, by examining its impact on cardiovascular, somatic physiological, social, and cognitive outcomes.

Inclusion Criteria:

• Experiment 4A: We will follow the standard exclusion protocol used in previous Fit & Strong! studies (e.g., Hughes et al., 2004; 2006). The participant's physician will be contacted for clearance to participate if they have a history of high blood pressure, or experience dizziness, lightheadedness, or chest pain or pressure during physical activities (walking, climbing stairs, and household chores, etc.) (see document: "E4_NeedforPhysicianScreeningQuestionnaire.docx"). Additionally, physicians will be contacted if participants indicate that they fall, feel unsteady, or use an assistive walking or standing device. For these conditions and any special considerations that a participant may express, physicians will be contacted for clearance.

Experiment 4B: Only participants who participated in Experiment 4A are eligible to participate in Experiment 4B.

Exclusion Criteria:

• Experiment 4A: We will follow the standard exclusion protocol used in previous Fit & Strong! studies (e.g., Hughes et al., 2004; 2006). For instance, participants will be excluded for joint steroid injections within 3 months, knee or hip surgery within the previous 6 months or next year, rheumatoid arthritis or other systemic inflammatory arthritis, or uncontrolled diabetes. The participant's physician will be contacted for clearance to participate if they have a history of high blood pressure, or experience dizziness, lightheadedness, or chest pain or pressure during physical activities (walking, climbing stairs, and household chores, etc.) (see document: "E4_NeedforPhysicianScreeningQuestionnaire.docx"). Additionally, physicians will be contacted if participants indicate that they fall, feel unsteady, or use an assistive walking or standing device. For these conditions and any special considerations that a participant may express, physicians will be contacted for clearance (see document: "StatementofMedicalClearanceforExercise.docx" and "CoverLetterforMedicalClearanceforExercise.docx").

Experiment 4B: Participants who did not participate in Experiment 4A are not eligible to participate in Experiment 4B.