Inclusion Criteria - Patients:  Scheduled to receive an autologous or allogeneic HCT. Being married or in a committed cohabiting relationship. English speaking and comprehending. Physician approval to participate in a walking program.  Inclusion Criteria - Caregivers:  Married to or in a cohabiting relationship with the patient. Able to participate in a walking program.  Exclusion Criteria - Patients:  Not scheduled to receive an HCT or already post-HCT. Unmarried or not in a committed cohabiting relationship. Non-English speaking and comprehending. Not medically approved to participate in walking program. Enrolled in competing behavioral intervention.  Exclusion Criteria - Caregivers:  Not married to or partnered/ cohabiting with the patient. Unable to participate in a walking program.