Will the integration of a patient-centered exercise prescription and supportive counseling attenuate declines in physical activity during radiation therapy? To address this question, this study will assess the feasibility of a patient-centered walking program for breast and head-and-neck cancer patients undergoing radiation therapy. Follow-up monitoring sessions will be scheduled to help provide support and ongoing counseling to facilitate increased activity (through walking) during radiation therapy. We will also examine the effect of the walking program on other outcomes such as happiness, depression and sleep to determine point estimates and measures of variability to inform future research.