DISEASE CHARACTERISTICS:

* Participants must be women with a previous diagnosis of stage I, II, or III invasive breast cancer or colorectal cancer

* Participants must have no evidence of disease at the time of registration and no history of metastases (M0)
* Participants must have a body mass index ≥ 25 kg/m\^2 measured within 28 days of registration
* Participants must be considered sedentary (defined as \< 60 minutes of moderate to vigorous physical activity per week; moderate exercise defined as exercising to the point of sweating)
* Participants must be willing to submit blood samples for biomarkers (insulin, glucose, HgbA1C, estradiol, and testosterone) and undergo DXA scans, and must be given the option to consent for specimen submission for banking and future translational medicine studies
* Participants must be willing and able to attend a Curves fitness center at least 3 times per week for 12 months

PATIENT CHARACTERISTICS:

* Participants must be post-menopausal, as defined by at least one of the following:

* At least 12 months since the last menstrual period
* Prior bilateral oophorectomy
* Previous hysterectomy with one or both ovaries left in place (or previous hysterectomy in which documentation of bilateral oophorectomy is unavailable) AND follicle-stimulating hormone (FSH) values consistent with the institutional normal values for the post-menopausal state

* If participant is under the age of 55, FSH levels must be obtained within 28 days prior to registration
* Zubrod performance status of 0
* Participants must have no abnormal changes on a regular (non-nuclear) cardiovascular exercise stress test (using a treadmill or bicycle) as measured by electrocardiogram (EKG)

* EKG must be within institutional limits of normal
* Results of previous cardiac exercise stress test may be used as long as it was done within 3 months prior to registration
* Participants must not have evidence of uncontrolled hypertension
* Participants with diabetes, pre-diabetes, and/or metabolic syndrome must have HgbA1C ≤ 8% within the past 28 days

* Current use of diabetes medications is allowed
* No other prior malignancy is allowed except for adequately treated basal cell or squamous cell skin cancer, in situ cervical cancer, or other cancer for which the participant has been disease-free for \> 5 years
* Participants must not be active smokers within past 90 days; active smoking is defined as any smoking, even a puff
* Participants must have regular access to the internet in order to receive monthly nutrition-program newsletter e-mails and to complete study questionnaires online
* Participants must be able to understand, speak, and read English
* Participants must have a home phone or cell phone and agree to participate in the 14 (40-minute) behavioral counseling sessions and 9 (20-30-minute) telephone interviews
* Participants must have a baseline physical exam and physician clearance (primary care provider, medical oncologist, or surgical oncologist) to participate in the weight loss and exercise prior to enrollment within 60 days of registration; copy of physician clearance document must be submitted

PRIOR CONCURRENT THERAPY:

* Participants must be 90 days to 730 days post-surgery, chemotherapy, and radiation therapy

* Current hormonal therapy is allowed among breast cancer participants
* Other concurrent anti-cancer therapies, including Herceptin, are not allowed
* Surgery is defined as any major surgical procedure (resection or reconstructive) that would preclude inclusion in the exercise program

* If the participant has had a remedial surgical procedure (e.g., revision of reconstruction) or persistent complications from her original operation, approval will be obtained from the participant's surgeon prior to enrollment

* Persistent complications may include, but are not limited to, prolonged wound healing, hernias, or ostomy prolapse