I once spent a week on a project with a colleague who's, let's say, kinda intense... You know smart guy and hard worker, but he always wanted to have the last word, whenever you explained something he never really believed you until he tried himself... Whatever, his work was ok, but as a person he was really exhausting. He left the customer's before I did, the first evening I was alone I was so people-tired that I didn't even go to the restaurant (it was in the hotel!), I stopped for groceries at a supermarket and ate in my room!