This study is being done to determine whether a telephone-based counseling intervention can help survivors of breast and colorectal cancer increase their weekly physical activity. Observational evidence suggests that physical activity after breast and colorectal cancer diagnosis decreases recurrence rates. Unfortunately, many people become less active during cancer therapy, and a substantial proportion never return to pre-diagnosis levels of physical activity. This study looks to see if people who have recently finished chemotherapy for breast, colon or rectal cancer can be motivated to increase their exercise by talking to an exercise specialist over the phone. The study also looks at changes in mood, fatigue, fitness, fat distribution and weight.

Inclusion Criteria:

• Histologically confirmed stage I-III breast or colorectal cancer
• 18 years of age or older
• Completed adjuvant treatment(for current malignancy)
• Completion of all adjuvant chemotherapy and radiation (with the exception of adjuvant herceptin and/or tamoxifen/aromatase inhibitor therapy for breast cancer patients) between 2 and 36 months prior to enrollment
• Ability to speak and read English
• Willingness to be randomized
• Medical clearance from an oncologist or primary care physician stating the participant is able to participate in an unsupervised, moderate-intensity physical activity program
• No major surgery within 2 months of study enrollment or planned during study period

Exclusion Criteria:

• Metastatic cancer
• Uncontrolled intercurrent illness including, but not limited to, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness that would limit compliance with study requirements
• Plans to have hip or knee replacement within a year
• Participation in more than 60 minutes a week of moderate-intensity recreational activity as assessed by the International Physical Activity Questionnaire Short Form
• BMI >47