The purpose of this study is to examine the feasibility and acceptability of a strength training-based intervention on exercise adherence among low active (defined as engaging in physical activity 90 minutes or less per week), pre-menopausal women ages 40-50, along with the effect on weight and various psychosocial measures. Participants will be randomly assigned to a strength training-based intervention or a wait-list control each lasting three months (participants in the no contact, wait-list control condition will have the option of receiving the strength training-based intervention following the three months).

Participants will be randomly assigned to a strength training-based exercise intervention or a no contact, wait-list control each lasting three months (participants in the no contact, wait-list control will have the option of receiving the strength training-based intervention following the three months). The strength training-based exercise intervention will be delivered via group-based Zoom sessions, motivational email messages, and a website. Participants will take part in two group-based Zoom exercise sessions (40-minute exercise sessions and 20 minutes of motivational counseling) and two individual exercise sessions per week for six months. Exercise sessions will include a combination of various aerobic (e.g., jogging in place, high knees) and muscle strengthening exercises (e.g., burpees, push-ups, lunges, body weight squats) designed to keep heart rate in the 60-85% range of maximum heart rate. Participants will choose from a variety of options for their two individual sessions (e.g., online exercise video, jogging or walking outside, prescribed exercise session listed on the website, or any other exercise) and modifications for each exercise will be made depending on the participant's ability and current fitness and strength level (e.g., wall push-ups vs. knee push-ups vs. regular push-ups). Participants will be instructed to stop exercising if problems occur and will receive training and handouts on how to recognize problems such as angina and myocardial infarction symptoms.

Self-Determination Theory (SDT) and habit formation theory will guide the content of the counseling portion of the Zoom sessions and the motivational features of the study website and text messages. Motivational counseling will be focused on increasing motivation to exercise and habit formation. The goal is to achieve integrated regulation and therefore, the health counselor will focus on positive affective response to exercise sessions and discuss how being physically active is becoming part of their self-identity. The goal will be high intrinsic motivation (i.e., individuals engage in exercise due to inherent pleasure) since it is related to higher levels of exercise. Strength training-based participants will also receive access to a mobile phone-friendly study website and will receive emails. Both the website and email messages will contain motivational content to complete the exercise sessions. The motivational website will also include an online log to track completion of home-based sessions and options for individual-based exercise sessions.. Assessment of exercise adherence, weight, and psychosocial variables will occur at baseline and three months.

Inclusion Criteria:

• 1) pre-menopausal women ages 40-50 years; (2) engaging in 90 minutes or less of exercise per week; (3) no exercise contraindications; (4) adequate space at home to complete exercise sessions and capacity to use Zoom via a mobile device or computer; (5) available to attend two zoom-based sessions a week; (6) be able to read, understand, and speak in the English language (7) willing to be randomly assigned to either study condition (8) access to iPhone 8 or later with iOS 16 or later

Exclusion Criteria:

• Specific exclusion criteria will include a history of coronary heart disease (history of myocardial infarction, symptoms of angina), orthopedic problems that would limit physical activity participation, diabetes, stroke, osteoarthritis, and any other medical condition that may make physical activity unsafe or unwise. Other exclusion criteria will include current or planned pregnancy, psychosis or current suicidal ideation, and psychiatric hospitalization within the last six months.