Rationale for intervention to be studied: This research design has several advantages. Group 1 will serve as the intervention follow-up to assess retention or non-retention of change due to the intervention on the outcome variables. Group 2 will serve as a lead-in to assess stability of the outcome variables prior to the intervention. Additionally, because of tremendous variability in the SCI population and difficulty with case-control matching, the cross-over design will help to control for variability between participants because each participant will serve as their own control. Veterans and nonveterans with SCI generally do not receive further structured rehabilitation once they have completed the acute and sub-acute phases of their rehabilitation. As such, the usual lifestyle activities have been chosen as the control for this study. Dr. Spungen has discussed the optimal control for an exoskeletal-assisted walking program. She has consulted with the Chiefs of several SCI Services in both the VA and non-VA rehabilitation hospitals. A case-controlled, matched RCT study would be strongest with two interventions: exoskeletal-assisted walking compared with any other form of physical activity such as robotically assisted body weight supported treadmill training (Lokomat), body weight supported treadmill training, arm ergometry etc. However, there are two considerations that make this type of study not feasible. One is that it would be extremely difficult to case-control match for independent variables within site, and the second is that most participants would likely not agree to participate if there was a 50% chance they would not get the exoskeletal-assisted walking arm. In order to control for an attention effect, participants in the UA arm will keep weekly activity logs and be contacted by phone calls from the study team to receive attention and encouragement to continue participation in the UA of their choice. In order to control for attention aspects of this type of study, participants will also make in person twice monthly visits to their sites during the UA arm. During these visits, study team staff will review their UA logs and administers the 10Q BFS and BSS.