Improving Exercise Capacity With a Tailored Physical Activity Intervention

Primary Objective: To determine if a \>10% difference exists in the % change (i.e., 2.06 ml/kg/min difference) in peak VO2 (volume or amount of oxygen your body consume) from baseline to 6 months of intervention between participants receiving the Physical Activity Intervention (PAI) versus Healthy Living Intervention (HLI). Secondary Objectives: * To determine if a \>10% difference exists in the % change in peak exercise cardiac output, calculated A-VO2 difference, and pre-exercise measures of left ventricular function from baseline to 6 months of intervention between participants receiving the PAI versus HLI. * Among these same participants, 1) to compare PAI and HLI groups on their baseline to 3 \& 6 months after initiating cancer treatment changes in 6-minWD, Health-Related Quality of Life (HRQOL), fatigue, strength, physical activity, cognitive \& physical function, 2) to determine the relationships between the 6-month time-dependent changes in these and peak VO2; and 3) to examine whether time-dependent changes in peak exercise cardiac output and/or calculated arteriovenous oxygen difference are associated with similar time-dependent changes in peak VO2. * Assess physical activity engagement via accelerometry.