Participants will receive lessons about positive psychology (PP) strategies, weekly goals for PP exercises, and in-app health-related messages that include reminders to practice PP exercises.

Participants will receive weekly individual videochat sessions with a health coach.

Number of days red foods (high-calorie, high-fat foods) are tracked, as measured by the food log data in the AYA Connect app. Participants will be asked to log their red foods in the app daily.

Number of days physical activity is tracked, as measured by activity tracker

Number of days weighed, as measured by smart scale

Change in weight, as measured by smart scale, from baseline to 3 and 6 months.

Change in energy intake (kcal), measured using the NCI Automated Self-Administered 24-hour Recall (ASA-24). The ASA-24 will be administered on one weekend day and one week day per assessment period to estimate energy intake.

Change in saturated fat intake (% kcal), measured using the NCI Automated Self-Administered 24-hour Recall (ASA-24 The ASA-24 will be administered on one weekend day and one week day per assessment period to estimate saturated fat intake.

Change in fruit and vegetable consumption (cups), measured using the NCI Automated Self-Administered 24-hour Recall (ASA-24). The ASA-24 will be administered on one weekend day and one week day per assessment period to estimate average fruit and vegetable consumption.

Change in fiber consumption (g), measured using the NCI Automated Self-Administered 24-hour Recall (ASA-24). The ASA-24 will be administered on one weekend day and one week day per assessment period to estimate fiber consumption.

Change in Healthy Eating Index (HEI) score, measured using the HEI and the NCI Automated Self-Administered 24-hour Recall (ASA-24). The ASA-24 will be administered on one weekend day and one week day per assessment period to estimate HEI. HEI scores range from 0 to 100, with higher scores indicating greater adherence to the Dietary Guidelines for Americans.

Changes in weekly minutes of moderate-to-vigorous activity, computed from the participant's activity tracker data and averaged over a minimum of 4 out of a 7-day period. Participants will be instructed to wear the activity tracker at all times.

Changes in daily steps, were computed from the participant's activity tracker data and averaged over a minimum of 4 out of a 7-day period. Participants will be instructed to wear the activity tracker at all times.

Change in self-reported physical activity, measured using the Paffenbarger Activity Scale (PAQ). The PAQ provides an estimate of minutes per week of moderate-to-vigorous intensity, and calories/week of light (5 kcal/min), medium (7.5 kcal/min), and high (10 kcal/min) intensity activities. PAQ changes have been predictive of weight change.

Change in frailty index, measured using the FRAIL Questionnaire. The FRAIL Questionnaire assesses: 1) self-reported fatigue (1 item from Patient-Reported Outcomes Measurement Information System (PROMIS) Global Health), 2) weight loss, 3) comorbidities (11 items from UNC Health Registry Comorbidity Assessment), 4) difficulty with ambulation (1 item from PROMIS Global Health), and 5) ability to overcome resistance (1 item from Medical Outcomes Study 36-Item Short Form). Positive responses for these components are summed to create the FRAIL index (range 0-5). A value > 3 is considered frail, and a value of 2 is considered prefrail.

Change in health-related quality of life, measured using the Medical Outcomes Study 36-Item Short Form (SF-36) survey. This survey includes 36 items with eight subscales (physical functioning, role limitations due to physical problems, social functioning, bodily pain, general mental health, role limitations due to emotional problems, vitality, and general health perceptions). Responses are coded on a scale of 0 to 100, where 0 is the worst possible health and 100 is the most favorable health score. The coded responses will be summed to yield a Physical Component Summary (PCS) score and a Mental Component Summary (MCS) score.

Change in depressive symptoms, measured by the Center for Epidemiological Studies Depression Scale (CES-D). The CES-D is a self-report depression scale including 20 items that relate to depressive feelings and behaviors during the past week. Response options range from 0 (rarely or none of the time) to 3 (most or almost All the Time). Scores range from 0 to 60, with high scores indicating greater depressive symptoms.

Change in anxiety symptoms, as measured using the Generalized Anxiety Disorder 7-item scale (GAD-7). Possible scores range from 0 to 21, with higher scores reflecting greater symptom severity; cut-points of 5, 10, and 15 correspond to mild, moderate, and severe levels of anxiety.

Change in perceived stress, measured by the 10-item Perceived Stress Scale (PSS-10). PSS-10 measures overall perceived stress during the past month. Factor analysis supports a two-factor correlated model with perceived self-efficacy and perceived helplessness subscales.

Change in positive and negative affect, measured using the Positive and Negative Affect Schedule (PANAS). PANAS is a 20-item scale divided into two subscales to measure positive and negative affect. Each item is rated on a five-point Likert scale from 1 (very slightly or not at all) to 5 (extremely) and are summed to yield scores for each subscale.