Brief Summary: This clinical trial evaluates the feasibility of exercise during chemotherapy in older women with stage I-III breast cancer. Previous studies have reported that exercise may reduce the chemotherapy-toxicity risk. This trial may help researchers learn if engaging in a physical activity program is feasible in patients receiving chemotherapy for breast cancer.

Detailed Description: PRIMARY OBJECTIVE: I. Determine the feasibility of implementing a home-based exercise intervention in older adults receiving chemotherapy for early-stage breast cancer. SECONDARY OBJECTIVES: I. Describe and determine the incidence of Common Terminology Criteria for Adverse Events (CTCAE) grade 3-5 toxicities overall and in three risk subgroups ("low-risk," "mid-risk" and "high-risk") determined by the Cancer and Aging Research Group-Breast Cancer (CARG-BC) tool. II. Evaluate the accuracy of the CARG-BC tool in predicting the incidence of CTCAE grade 3-5 toxicities. III. Determine the incidence of dose-reductions, dose-delays, treatment discontinuation and reduced-dose intensity (RDI; defined as \< 85% of total dose) overall and in the three risk subgroups. IV. Determine the incidence of hospitalizations overall and in the three risk subgroups. V. To examine the effect of the intervention on quality of life overall and in the three risk subgroups, as assessed by the Functional Assessment of Cancer Therapy-Breast (FACT-B) and Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F). VI. To examine the effect of the intervention on function overall and in the three risk subgroups. VII. To examine the effects of the intervention on patient expectation and self-efficacy, as assessed by Outcomes Expectations for Exercise (OEE) and Perceived Self-Efficacy for Fatigue Self-Management (PSEFSM) respectively. OUTLINE: Patients participate in one-on-one coaching sessions with a health coach once a week (QW) to discuss the content offered in the program, and challenges they are currently facing in achieving their exercise goals. Patients receive a copy of the Walk with Ease Program (WWE) workbook, wear a fitness tracker and are encouraged to achieve 150 minutes of walking per week during chemotherapy and up to 1 month after chemotherapy. Patients also participate in the Growing Stronger Strength Training Program and receive instruction manuals. They perform the initial 2 exercises 2 days per week for 4 weeks, and subsequent 2 exercises 2 days per week for the remainder of the chemotherapy course. Patients maintain exercise logs and complete questionnaires over 30-45 minutes at baseline, end of chemotherapy and at 1 month after chemotherapy.