Investigating Gains in Neurocognition in an Intervention Trial of Exercise

Inclusion Criteria: * Men and women 65 - 80 yrs * Ambulatory without pain or the assistance of walking devices * Able to speak and read English * Exercise level of \<60 minutes per week (less than 20 minutes / 3 days week) * Medical clearance by PCP * Living in community for duration of the study * Reliable means of transportation * No diagnosis of a neurological disease * Eligible to undergo MRI Exclusion Criteria: * Current diagnosis of a DSM-V Axis I or II disorder including Major Depression * History of major psychiatric illness including schizophrenia (not including general anxiety disorder or depression) * Current treatment for cancer - except non-melanoma skin * Neurological condition (MS, Parkinson's, Dementia, MCI) or brain injury (traumatic or Stroke) * Type I Diabetes or insulin-dependent diabetes * Current alcohol or substance abuse * Current treatment for congestive heart failure, angina, uncontrolled arrhythmia, DVT or other cardiovascular event * Myocardial infarction, coronary artery bypass grafting, angioplasty or other cardiac condition in the past year * Regular use of an assisted walking device * Presence of metal implants (pacemaker, stents) that would be MR ineligible * Claustrophobia * Color Blindness * Not fluent in English * Not medically cleared by PCP * Engaging in \>60 minutes of moderate intensity physical activity (more than 20 minutes day / 3 days per week) * Traveling consecutively for 3 weeks or greater during the study