Previous research suggests that regular physical activity may make cancer survivors do better in the long run. Laboratory studies suggest that stress may be bad for cancer patients as well. The investigators are interested in whether yoga, a practice that combines physical activity and stress reduction, is beneficial to cancer survivors. To answer that question, the investigators will need to do a large scale clinical trial.

Before the investigators can do that large study, they need to know whether people are willing to participate in this kind of study, whether they can do the yoga practice regularly and for how long, what kind of changes they may experience in how they can handle their daily activities, emotion, sleep, memory and problem solving ability, and what are the changes that can happen in their body after doing the yoga practice. Answering these questions is what this study is about.

Inclusion Criteria:

• Woman age 18 or older
• History of stage 0-III breast cancer or stage I-III ovarian cancer; all antitumor therapies, excluding hormonal therapy, have been completed at least 60 days prior to enrollment
• ECOG Performance Status 0-1 (within 90 days of enrollment)
• Sedentary: <90 minutes/week of moderate-intensity (not exhausting, light perspiration, e.g. fast walking, tennis, easy bicycling, easy swimming, popular and folk dancing) physical activity during the preceding 2 months, and <30 minutes/month of any high-intensity activity (heart beats rapidly, sweating, e.g. running, aerobics classes, cross country skiing, vigorous swimming, vigorous bicycling) in the past 2 months

Exclusion Criteria:

• Evidence of active malignant disease
• Currently has breast implant (which limits the performance of many yoga poses)
• Significant cardiopulmonary disease, severe arthritis, glaucoma or any other medical conditions that make yoga practice unsafe as determined by a study investigator.
• Patient requires regular use of beta blockers or calcium channel blockers.
• Use of any medication that would interfere with the study's initial blood tests, including insulin or insulin secretagogues, corticosteroids, daily use of NSAIDs (except aspirin at no more than 81 mg/day) within 7 days of the initial study blood test.
• Unlikely to be compliant with the study intervention