It is widely known that physical activity is important for health and wellbeing, yet most Americans do not meet recommended levels of activity. People may commonly believe that only the actual amount of physical activity matters for health and wellbeing. However, the investigators propose that individuals' mindsets about the adequacy of their level of physical activity and its corresponding health consequences (activity adequacy mindsets) affect health outcomes, over and above their actual level of physical activity. In recent years, health technologies such as wearable fitness trackers have become popular tools to promote higher levels of physical activity. This study leverages the tracking and feedback capabilities of Apple Watch to study the effects of mindsets about physical activity on health and wellbeing, as well as the pathways through which these effects may occur.

Study Overview: This study examines how individuals' mindsets about the adequacy of their level of physical activity and its corresponding health consequences (activity adequacy mindsets) affect health outcomes. Participants attend an "onboarding" lab session in which they complete physiological, cognitive, and psychological measures and receive an Apple Watch to wear for the following 5 weeks. The Watch is equipped with a step count tracking app. No step count feedback is provided in week 1 as a baseline; starting in week 2, participants are randomized to 4 conditions in which either 1) accurate, 2) inflated, or 3) deflated step count is displayed on the watch in order to manipulate participants' perceived physical activity, independently of their actual physical activity. In condition 4, participants receive a meta-mindset intervention in addition to accurate step count feedback. Throughout the 5 weeks, participants complete short daily surveys and longer weekly surveys administered online. Finally, participants come in for an "offboarding" lab session in which the same measures are collected as in the onboarding session.

Participants: Participants will be 160 healthy adults recruited from the community, 40 per condition.

Main Hypotheses: This is a largely exploratory study, examining various mechanisms through which activity adequacy mindsets may affect health and wellbeing. Tests include (but are not limited to) the following key hypotheses:

H1) Inflated step count feedback (compared to accurate feedback) leads to a more positive activity adequacy mindset, and deflated feedback (compared to accurate feedback) leads to a more negative activity adequacy mindset (see Primary Outcome Measures).

H2) Activity adequacy mindset influences health and wellbeing (see Primary Outcome Measures) over and above actual physical activity.

H3) Activity adequacy mindset influences health and wellbeing through various mechanisms (see Secondary Outcome Measures):

H3a) Affective mechanism: A more positive (vs. negative) activity adequacy mindset leads to more positive everyday affect (incl. higher satisfaction, lower anxiety, lower stress). Positive affect in turn improves health and wellbeing.

H3b) Motivational/ behavioral mechanism: A more positive (vs. negative) activity adequacy mindset leads to higher motivation to exercise and improve one's health, as well as higher exercise self-efficacy. Higher motivation and self-efficacy in turn lead to higher levels of actual physical activity, which in turn improve health and wellbeing.

H3c) Placebo mechanism: A more positive (vs. negative) activity adequacy mindset directly improves health and wellbeing through placebo/ nocebo effects.

H4) A meta-mindset intervention teaching people about activity adequacy mindsets leads them to adopt more positive mindsets, which in turn predicts improved health and wellbeing through the mechanisms described under H3. That is, compared to accurate step count feedback only, accurate feedback plus meta-mindset intervention leads to improved health and wellbeing.

Inclusion Criteria:

• Low level of physical activity in the prior six months, as indicated by self-report
• Walking as primary source of physical activity in the prior six months, as indicated by self-report
• Ability to understand study procedures and to comply with them for the entire length of the study.

Exclusion Criteria:

• Candidates who answer affirmatively to any of the Physical Activity Readiness Questionnaire (PAR-Q) items will be excluded, unless they get clearance from a physician that they are able to participate in the study.
• Candidates who report pregnancy will be excluded, as natural changes in weight and body composition during pregnancy would invalidate our results.

If made publicly available, all data will be de-identified and the anonymous data will be shared with researchers on the Open Science Framework