When you are officially out of fantasies, is when you can’t go to sleep any more. This mostly happens when you spend days after days at home, doing nothing. Your mind uses up every bit of fantasy it has and eventually runs out of fantasies. The problem is that your mind is very much able to fantasize but it doesn’t have the ability to make new ones. You cannot just sit there and expect your mind to come up with new fantasies. This is not how it works. Fantasies are out there. You should go out and get them. This is why if anyone ever asks me what I do out there, I would like to answer I go fantasy hunting all day.