Cant seem to move my a#@

Well after 12years of working as an RN in a hospital I finally had enough and quit my job. I began working in longterm healthcare in Oct of last year. Now I use to work 3 12hr shifts weekly 7a to 7pm. Now I work 5 8hr shifts 2pm to 10pm. I really enjoy this new job and find it much less stressful. But I cant seem to find any energy to walk or do much of anything else. I am so tired all of the time. I am really trying to get my mojo back but its hiding. Anyone have any suggestions.