Absolutely the worst thing about this job is the travel and being away from family. I have a wife and three wonderful children the kids are all active in sports and it's very difficult to up and leave and miss them growing up.
When you get just a complete sense of blackness or void ahead of you that somehow the future looks an impossible place to be and the direction you are going seems to have no purpose there is this word despair which is a very awful thing to feel.