The purpose of this study is to develop and test a brief program to help overweight people become more physically active. We plan to design a program that teaches people how to become more active by identifying how fitness enables them to live their lives better.

Participants will be asked to complete questionnaires and wear a device that tracks their exercise for 1 week. If accepted into the study, they will receive a 1 day program designed to help them exercise more. Then they will receive phone calls and emails for support after the program. Finally, participants will come in 3 and 6 months after the program to complete the same questionnaires and wear the exercise tracker again.

The study is primarily interested in increasing exercise levels, and so we hope to see participants exercising more after the program than they were before. We will also ask them questions (via the questionnaires) that tell us the degree to which they are exercising based on their one desires and values, as opposed to doing it because they were told to.

Despite the importance of adoption and maintenance of habitual moderate to vigorous-intensity physical activity (MVPA) for health benefits and long-term weight management, current comprehensive lifestyle interventions place little emphasis on physical activity behavior change strategies and have only modest impact on MVPA. Acceptance and Commitment Therapy (ACT), a well validated, newer generation behavioral approach uses values of clarification and commitment strategies, along with acceptance-based skills training, to effect health behavior change that is consistent with personally identified values. ACT presents a theoretically consistent and potentially powerful intervention framework from which to target values-based autonomous motivation and increase MVPA. The overall aim of this study is to test the feasibility, acceptability, and preliminary efficacy of an ACT-based workshop intervention for increasing bout-related MVPA for overweight and obese, insufficiently active adults using a single-arm design. We will recruit 48 overweight/obese, insufficiently active adults across multiple cohorts and provide them with a 4-hour, ACT-based workshop followed by weekly emails and monthly phone calls for 3 months. The primary goal of the workshop is to use values clarification and acceptance-based skills training to increase values-based autonomous motivation and bout-related MVPA. Participants will self-monitor and report on progress via weekly emails and monthly phone calls. Assessments will be at baseline, 3, and 6 months. The goal of this study is threefold: 1) to determine the feasibility and acceptability of the ACT workshop intervention by assessing the completion of the intervention at all time points and via questionnaires; 2) to show changes in autonomous motivation and values-consistent behavior at the end of the intervention; and 3) to show changes in physical activity, by use of an objectively measured physical activity devices, where participants are engaging in at least 200 minutes of MVPA at 3 and 6-months)

This study will be conducted at the Miriam Hospital Weight Control and Diabetes Research Center by Drs. Jason Lillis and Dale Bond.

Inclusion Criteria:

• Body mass index (BMI) between 25-45 kg/m2
• Report being insufficiently active (i.e., <150 minutes per week of bout related MVPA)

Exclusion Criteria:

• Unable to engage in physical activity safely due to medical status
• Unable to read or understand study materials
• Currently in another physical activity or weight control program
• Currently taking medications that cause dizziness or feeling faint while standing (e.g., some hypertension medications
• Report any condition that would preclude adherence to the intervention protocol (e.g., current or past substance use disorder or psychiatric hospitalization)
• Plans to relocate during the study timeline
• Terminal illness diagnosis