Inclusion Criteria:  Pancreatic or gastric adenocarcinoma, biopsy-proven Have completed or are within 2 weeks of completion of preoperative chemoradiotherapy either on- or off-protocol Anticipated to undergo potentially curative resection in 4-6 weeks from enrollment Able to understand the description of the study and willing to participate Able to understand the exercise program Able to independently maintain daily exercise logs via Pt Pal -iOS, Android or desktop web browser on their own personal device Telephone or email access and agreement to engage with the research personnel via phone or email Meet all screening requirements, including physician clearance >= age 18  Exclusion Criteria:  Non-English speaking Has participated in moderate to high intensity strengthening exercises at least two times per week within the past four weeks prior to enrollment Unable to complete the baseline assessment questionnaires or functional assessments Underlying unstable cardiac or pulmonary disease or symptomatic cardiac disease (New York Heart Association functional class III or IV) Recent fracture or acute musculoskeletal injury that precludes the ability to weight bear fully on all 4 limbs in order to participate in an exercise intervention Numeric pain rating scale of >= 7 out of 10 Myopathic or rheumatologic disease that impacts physical function Recurrent cancer following prior resection < age 18