The Repetitive Thinking Questionnaire- 10 item form is a well-validated measure that assesses trait-like repetitive negative thinking (e.g., worry, cognitive rumination) during times of distress. Participants respond to ten items, rated on a 5-point Likert scale (1 - Not true at all to 5 - Very True) to indicate to what extent they agree with each statement. Higher scores on the measure indicate greater trait engagement in repetitive negative thinking. Total possible scores range from 10 to 50.

The Snaith-Hamilton Pleasure Scale is a measure which assesses participant capacity to experience pleasure in the past few days. Participants respond to fourteen items, rated on a 4-point Likert scale (0 - Strongly disagree to 4 - Strongly agree) to indicate their hedonic capacity over the last few days. Higher scores on the measure indicate greater hedonic capacity, or capacity to experience pleasure. Total possible scores range from 0 to 56.

The Behavioral Inhibition and Behavioral Activation Scale- Inhibition subscale is a well-validated measure that assesses for trait-like behavioral inhibition, similar to overcontrol. Participants respond to seven items, rated on a 4-point Likert scale (1 - Very true for me to 4 - Very false for me) to indicate their general behavioral inhibition. Higher scores on the measure indicate higher inhibition. Total possible scores range from 7 to 28.

The Behavioral Inhibition and Behavioral Activation Scale- Activation Drive subscale is a well-validated measure that assesses for trait-like behavioral drive, similar to goal seeking activation. Participants respond to four items, rated on a 4-point Likert scale (1 - Very true for me to 4 - Very false for me) to indicate their general behavioral drive. Higher scores on the measure indicate higher drive/goal seeking. Total possible scores range from 4 to 16.

The Behavioral Inhibition and Behavioral Activation Scale- Activation Fun Seeking subscale is a well-validated measure that assesses for trait-like behavioral fun seeking, similar to excitement seeking and surgency on other measures of activation. Participants respond to four items, rated on a 4-point Likert scale (1 - Very true for me to 4 - Very false for me) to indicate their general levels of fun/excitement seeking. Higher scores on the measure indicate higher fun seeking. Total possible scores range from 4 to 16.

The Behavioral Inhibition and Behavioral Activation Scale- Activation Reward Responsiveness subscale is a well-validated measure that assesses for trait-like behavioral sensitivity to reward. Participants respond to five items, rated on a 4-point Likert scale (1 - Very true for me to 4 - Very false for me) to indicate their general levels of reward sensitivity. Higher scores on the measure indicate higher pleasure from reward and reward seeking. Total possible scores range from 5 to 20.

The Quality of Life Enjoyment and Satisfaction Questionnaire is a measure which assesses current levels participant satisfaction in many domains of their life (e.g., social and romantic relationships, work/school, health, overall wellbeing). Participants respond to sixteen items, rated on a 5-point Likert scale (1 - Very Poor to 6 - Very Good) to indicate their levels of quality of life and life satisfaction during the past week. Higher scores on the measure indicate greater satisfaction. Total possible scores range from 16 to 80.

The Dimensional Anhedonia Rating Scale is a measure which assesses participant current levels of hedonic capacity, or ability to feel pleasure. Participants fill in two experiences that they typically enjoy across four domains (favorite sensory experiences, favorite foods, favorite social activities, favorite pastimes/hobbies) and then rate how much they would enjoy, spend time on, desire for, and interest of each domain, rated on a 5-point Likert scale (1 - Not at All to 5 - Very Much). These ratings are summed to index overall desire for, satisfaction with, and likelihood of pursuing favorite activities at the trait-level (i.e., no specific timeframe). Higher scores indicate greater hedonic capacity. Total possible scores range from 16 to 80.

The Intolerance of Uncertainty Scale is a measure which assesses trait-like tolerance of uncertainty across numerous life domains. Participants respond to 27 items, rated on a 5-point Likert scale (0 - Not at all characteristic to 4 - Entirely characteristic) to indicate their general tolerance of uncertainty. Higher scores on the measure indicate greater intolerance of uncertainty. Total possible scores range from 0 to 108.

The Multidimensional Psychological Flexibility Inventory (short form)- Flexibility Subscale is a measure which assesses various aspects of psychological flexibility in line with the hexaflex model of psychological flexibility. Participants respond to twelve items, rated on a 6-point Likert scale (0 - Never true to 5 - Always true) to indicate their level of agreement with each statement regarding facets of flexibility over the past two weeks. Higher scores on the subscale indicate greater flexibility. Total possible scores range from 0 to 60.

The Multidimensional Psychological Flexibility Inventory (short form)- Inflexibility Subscale is a measure which assesses various aspects of psychological inflexibility in line with the hexaflex model of psychological flexibility. Participants respond to twelve items, rated on a 6-point Likert scale (0 - Never true to 5 - Always true) to indicate their level of agreement with each statement regarding facets of inflexibility over the past two weeks. Higher scores on the subscale indicate greater inflexibility. Total possible scores range from 0 to 60.

The Self-Compassion Scale Short Form is a measure which assesses an individual's general level of self-directed compassion when they are going through difficulties. Participants respond to twelve items, rated on a 5-point Likert scale (1 - Almost Never to 5 - Almost Always) to indicate their level of agreement with each statement regarding how self-compassionate they are with themselves. Higher scores on the scale indicate greater levels of self-compassion. Total possible scores range from 12 to 60.

The Becks Depression Inventory II is a measure which assesses participant current levels of depression over the past two weeks. Participants respond to 21 items, rated on a 4-point Likert scale (0 - Not at all to 3 - Completely) to indicate how much they feel each symptom of depression. Higher scores on the measure indicate greater depression. Total possible scores range from 0 to 63.