ACT to Reduce Morbidity and Mortality in Hematopoietic Stem Cell Transplant Patients

Patient Inclusion Criteria: * Ability of participant to understand this study, and participant willingness to sign a written informed consent. NOTE: Remote / electronic consent via REDCap consenting allowed per IRB policy and approval. * Stated willingness to comply with all study procedures and lifestyle considerations and availability for the duration of the study * Plan to undergo allogeneic HCT in approximately 30 days * Males and/or females age 18 - 80 years * Agreement to adhere to Lifestyle Considerations throughout study duration * Access to necessary resources for participating in a technology-based intervention (i.e., computer, smartphone, internet access). NOTE: A smartphone will be provided to participants if needed. * Able to read/write English or Spanish (as we lack trained ACT interventionists in other languages) Caregiver Inclusion Criteria: * Ability of participant to understand this study, and participant willingness to sign a written informed consent. NOTE: Remote / electronic consent via REDCap consenting allowed per IRB policy and approval. * Stated willingness to comply with all study procedures and lifestyle considerations and availability for the duration of the study * Males and/or females age 18-80 years * Agreement to adhere to Lifestyle Considerations throughout study duration * Access to necessary resources for participating in a technology-based intervention (i.e., computer, smartphone, internet access). NOTE: A smartphone will be provided to participants if needed. * Able to read/write English or Spanish (as we lack trained ACT interventionists in other languages) Patient Exclusion Criteria: * Caregiver unwilling to enroll (as standard of care, all HCT patients are required to have a caregiver, but caregivers may decline to participate in this study which would make the patient ineligible for this study) * Diagnosed with a psychiatric illness or is in a social situation that would limit compliance with study requirements * Concurrent participation in another behavioral intervention research study. * Activity restrictions that limit one's ability to engage in intense physical activity Caregiver Exclusion Criteria: * Patient unwilling to enroll * Diagnosed with a psychiatric illness or is in a social situation that would limit compliance with study requirements • Concurrent participation in another behavioral intervention research study. * Activity restrictions that limit one's ability to engage in intense physical activity