EMBark on RAdiation Therapy With a Clinic-based Exercise Program: EXERCISING TOGETHER

Inclusion Criteria: * INTERVENTION (SURVIVORS) INCLUSION * Histologically confirmed prostate cancer or breast cancer without evidence of metastatic disease * Confirmed by review of the electronic medical record (EMR) and subsequently recorded in Survivor Health History. In cases where the EMR isn't clear, their Oregon Health \& Science University (OHSU) provider will be contacted for confirmation. For non-OHSU patients, we'll initially collect their cancer health history by a self-report questionnaire and confirm when we receive the survivor's outside medical record (through a signed Release of Information) * Scheduled to receive radiation therapy for curative intent * Confirmed by review of the EMR and subsequently recorded in Survivor Health History. In cases where the EMR isn't clear, their OHSU provider will be contacted for confirmation/ For non-OHSU patients, we'll initially collect their cancer health history by a self-report questionnaire and confirm when we receive the survivor's outside medical record (through a signed Release of Information) * Co-residing with an intimate partner or spouse who is willing to participate * Confirmed by self-report on the Demographic Questionnaire * INTERVENTION (SURVIVORS AND PARTNERS) INCLUSION * 18 years of age and older * For survivors: confirmed by review of the date of birth as documented in the Electronic Medical Record (EMR) and subsequently recorded in Survivor Health History. For non-OHSU patients, we'll collect their age by self-report on the Survivor Health History * For partners: confirmed by self-report on the Health History Questionnaire * \< 2 structured strength training sessions for less than 30 minutes per week in the last month * Confirmed by self-report on Health History Questionnaire * Home internet sufficient for videoconferencing * Confirmed by staff review of Internet Connectivity Screening Guide with the participants and outcome recorded in a CRF * Signed informed consent * Confirmed by completion of e-Consent in REDCap * Willing to be randomized into either study arm and adhere to study protocol * Confirmed verbally with the participant and response documented in the Participant Tracking database * IMPLEMENTATION INCLUSION * Be one of these key stakeholders: patient, spouse/partner, healthcare providers, or administrator * Verbal informed consent following receipt of an Information Sheet Exclusion Criteria: * INTERVENTION (SURVIVORS AND PARTNERS) EXCLUSION * Cognitive difficulties that preclude answering the survey questions, participating in the exercise classes or performance tests, or providing informed consent * In the event of a suspected undeclared cognitive impairment, it will be confirmed by physician clearance or professional opinion of the Principal Investigator, Kerri Winters-Stone * A medical condition, movement or neurological disorder, or medication use that contraindicates participation in moderate intensity exercise. Specific contraindications include the following: poorly controlled diabetes, recent cardiac event, neuromuscular disease, untreated orthostatic hypertension, recent surgery, acute hernia, acute rheumatoid arthritis, severe memory disorders, severe balance disorder, inability to ambulate without a walker or wheelchair, inability to stand for 3 minutes, severe hearing or vision problem * Confirmed by a combination of reviewing the EMR, self-report on the Health History Questionnaire, Charlson Comorbidity Index questionnaire, and/or by physician clearance. If in the professional opinion of the Principal Investigator, Dr. Kerri Winters-Stone, contraindications other than those identified by the patient or physician are present, she may consider the participant ineligible. For Spouse/Partner: must answer \'No\' to American College of Sports Medicine pre-participation screening questions. If spouse/partner answers \'Yes\' to either question they may be required to obtain physician clearance prior to becoming eligible. Physician clearance may also be requested at the discretion of the principal investigator.