Identifying Best Approach in Improving Quality of Life and Survival After a Donor Stem Cell Transplant in Older, Medically Infirm, or Frail Patients With Blood Diseases

Inclusion Criteria: * Vulnerable patients as defined by one or more of the following criteria * Age 65 years or older * Having Hematopoietic Cell Transplantation - Comorbidity Index (HCT-CI) scores of \>= 3 (for patients that could be 20 years old and older) * Having frailty as determined by walk speed of \< 0.8 m/s using 4-meter walk test (for patients 50 years old and older) * Patients considered or referred for allogeneic HCT to treat a hematological malignant or non-malignant disease * Able to speak and read English - interaction with the interventionist trainer and endpoint measurement must occur in English * Willing and able to provide informed consent * Planned allogeneic HCT within 3 weeks - all types of donors and all sorts of conditioning regimens are allowed. Patients with suspected active disease (relatively old disease staging or relatively old intervention) or significant comorbidity (e.g. suspicious untreated pulmonary nodules) based on prior evaluations, that could delay the transplant would be considered for enrollment within a tighter window (10-14 days before allogeneic HCT) to allow for completed pre-HCT work-up evaluations that would confirm readiness to proceed with transplant * Able to exercise at low to moderate intensity, specifically taking into consideration the rare circumstances where subjects are not able to exercise due to either birth deformity or prior traumatic injury that affects their gait * Adequate cardiopulmonary reserve, as judg…