Iyengar Yoga for Chemotherapy-induced Fatigue in Breast Cancer Patients

Inclusion Criteria: * non-metastatic invasive breast cancer * currently receiving adjuvant chemotherapy * moderate to severe chemotherapy-induced fatigue * physical and cognitive capacity to participate in yoga or walking Exclusion Criteria: * diagnosed and pharmacologically treated psychiatric disorder except depressive adaptation disorder as a reaction to cancer diagnosis * ECOG status \> 1 * prior malignancy with a disease-free survival \< 10 years except curatively treated basalioma of the skin and carcinoma in situ of the cervix * prior ductal carcinoma in situ (DCIS) ot the breast * pregnancy or breastfeeding * regular practice of yoga or walking during the past 12 months