This study will test whether a physical activity intervention can improve cognition in breast cancer survivors and help the development of physical activity guidelines for cognition in breast cancer survivors.

Many breast cancer survivors experience problems with mental abilities such as memory, attention, and concentration (known as cognition). Increasing physical activity has been shown to improve cognition in adults; however, little is known about whether this is helpful for cancer survivors as well. This study will test whether a physical activity intervention can improve cognition in breast cancer survivors and help the development of physical activity guidelines for cognition in breast cancer survivors.

Inclusion Criteria:

• breast cancer survivors who have completed active treatment at least 6 months prior to enrollment and are within 5 years of diagnosis of stage 1, 2, or 3 breast cancer
• self-report difficulties with cognition since their cancer diagnosis
• self-report low levels of moderate to vigorous physical activity
• have a Fitbit compatible device with internet
• breast cancer was treated with chemotherapy and/or hormonal therapy

Exclusion Criteria:

• medical condition that could make it potentially unsafe to be in an unsupervised physical activity intervention
• currently taking tamoxifen or aromatase inhibitor that will be stopped in the next 6 months
• unable to commit to a 12-month study