Patient Health Questionnaire-9 before participating as a Peer Mentor, 6 weeks into participation as a Peer Mentor, and 12 weeks after starting as a peer mentor.

The Patient Health Questionnaire-9 is a 9-item measure used to assess frequency that a participant experiences depressive symptoms. Each item is score on a 4-point scale from 0 ("not at all") to 3 ("every day"). Higher total scores indicate more frequent experience of depressive symptoms.

Perceived Stress Scale 4 before participating as a Peer Mentor, 6 weeks into participation as a Peer Mentor, and 12 weeks after starting as a peer mentor.

The Perceived Stress Scale 4 measures participant perceptions of their thoughts and feelings over the past month on 4 items. Each item is scored on a 5-point scale from from 0 ("Never") to 4 ("Very Often"). Higher scores indicate higher levels of stress.

State Mindfulness Scale Physical Activity before participating as a Peer Mentor, 6 weeks into participation as a Peer Mentor, and 12 weeks after starting as a peer mentor.

The State Mindfulness Physical Activity scale is a 12 item measure with six items assessing state mindfulness of the mind (i.e., thoughts and emotions) and six items assessing state mindfulness of the body (i.e., movement, body sensations, muscle engagement). The response scale is 0 - 4, with anchors of Not at all (0) and Very much (4). Initial evidence supports a bi-factor structure of the measure in which both a general state mindfulness factor and two specific factors (mind and body) are supported. The bi-factor structure supports the use of using a single score to capture overall state mindfulness, but also the use of two scores capture mindfulness of the mind and mindfulness of the body.

Quiet Ego Scale before participating as a Peer Mentor, 6 weeks into participation as a Peer Mentor, and 12 weeks after starting as a peer mentor.

The Quiet Ego Scale is a 14 item measure that assesses detached awareness, inclusive identity, perspective taking, and growth. Each item is assessed on a 5-point Likert scale from 1 ("strongly disagree") to 5 ("strongly agree"). A higher score indicates a stronger quiet ego.

University of California Los Angeles Loneliness Scale 3 before participating as a Peer Mentor, 6 weeks into participation as a Peer Mentor, and 12 weeks after starting as a peer mentor.

The Loneliness Scale 3 comprises 3 questions that measure 3 dimensions of loneliness: relational connectedness, social connectedness, and self-perceived isolation. Each item is measured on a 3-point scale from 1 ("Hardly Ever") to 3 ("Often"). Higher scores indicate greater perceptions of loneliness.