Study participants that have survived endometrial cancer and healthy participants that have no history of invasive cancer.

Inclusion Criteria:

1. Survivor of endometrial cancer (survivor group only).
2. Was diagnosed with Stage I, II, or IIIa endometrial cancer in the past five years (survivor group only).
3. Completed surgical or radiation treatment at least 6 months ago (survivor group only).
4. No history of invasive cancer, except for non-melanoma skin cancer (no cancer history group).
5. Age 45 years of older (no cancer history group).
6. Female (no cancer history group).
7. Not pregnant by self-report (no cancer history group).
8. Speaks and reads English (all participants).
9. Oriented to person, place, and time (all participants).
10. Has clearance from their physician to engage in moderate physical activity (all participants).
11. For web-based maintenance intervention pilot study, women will be included if they have completed their third follow-up assessment.
12. For web-based maintenance intervention, women are considered ineligible if they do not have internet access.

Exclusion Criteria:

1. Engages in programmatic physical activity at moderate or greater intensity on five or more days per week for 30 minutes or more, or vigorous intensity activity 20 minutes or more at least 3 days per week, and have maintained this level of activity for six months or longer.
2. Have any condition defined by the American College of Sports Medicine's as "absolute contraindications to exercise testing" (a recent significant change in the resting ECG suggesting significant ischemia, recent myocardial infarction (within 2 days) or acute cardiac event; unstable angina; uncontrolled cardiac arrhythmias causing symptoms or hemodynamic compromise; severe symptomatic aortic stenosis; uncontrolled symptomatic heart failure; acute pulmonary embolus or pulmonary infarction; acute myocarditis or pericarditis; suspected or known dissecting aneurysm; acute infection).
3. Have any condition as defined by the American College of Sports Medicine's as "relative contraindications to exercise testing" (left main coronary stenosis; moderate stenotic valvular heart disease; electrolyte abnormalities; severe arterial hypertension at rest; hypertrophic cardiomyopathy and other forms of outflow tract obstruction; neuromuscular, musculoskeletal, or rheumatoid disorders that are exacerbated by exercise; high-degree atrioventricular block; ventricular aneurysm; uncontrolled metabolic disease; chronic infectious disease).
4. Right or left bundle branch block.
5. Baseline ST segment or T wave changes that would make monitoring of the ECG stress test indeterminate.
6. Uncontrolled asthma
7. Have other medical contraindications as defined by the patient's physician.