RecruitingBehavioural interventionHigh-Intensity Exercise and High-Fiber Diet for Immunotherapy Outcomes in Melanoma Patients: The DUO TrialThe purpose of this study is to determine whether high-intensity exercise and high-fiber diet are feasible and improve various health outcomes among participants with advanced melanoma receiving immunotherapy. The names of the groups in this research study are: * High-Intensity Exercise (EX) * High-fiber Diet (DT) * Combined High-Intensity Exercise and High-Fiber Diet (COMB) * Attention Control (AC)