The investigators hypothesize that two pelvic relaxation exercises will be feasible and safe to perform by subjects daily before radiation during the participant's treatment and will decrease variability of sacral slope measurements on daily port films. The investigators will observe trends in the daily variability and change in the sacral slope in each participant to determine if this could decrease variability. The investigators will compare these measurements to a retrospective cohort that did not have the exercises, but did demonstrate variability. Reducing set-up variability (which inadvertently occurs during radiation) is important to improve radiation targets and diminish potential adverse effects. The investigators will query participants for objective and subjective feedback on the exercises and record frequency and duration of the two exercises.

Inclusion Criteria:

• Patients will be >21 yrs of age and will have an oncologic diagnosis that requires a course of pelvic radiation therapy for a minimum of 5 weeks.
• They will have an ECOG Performance Status (This scale, developed by the Eastern Cooperative Oncology Group (ECOG), now part of the ECOG-ACRIN (American College of Radiology Imaging Network) Cancer Research Group, describes a patient's level of functioning in terms of their ability to care for themselves, daily activity, and physical ability (walking, working, etc.)) of 1 or better as determined by patient history.
• They will be ambulatory without needing any ambulatory aids such as a cane or walker.
• Both men and women will be eligible as there is no significant anatomical difference in sacral slope measurement. Joint replacement patients will not be excluded.

Exclusion Criteria:

• Adults unable to consent
• Individuals who are not yet adults (infants, children, teenagers)
• Pregnant women
• Prisoners
• Non-English speaking subjects