Physically and Mentally tired

The feeling of being so physically exhausted after reaching your limit of ahat your body can handle and then pushing your mind mentally so you can keep processing and staying awake days on end working hard non stop, I feel that way too often, maybe I push myself too much but it never feels like enough, I wish my body was not contained by this mortal being that I am. I want to do more but sometimes I can't do it all.
I feel exhausted, mentally and physically.