Never open your story with a character thinking, I advise my students. As a further precaution, don’t put a character in a room alone – create a friend, a bystander, a genie, for God’s sake, any sentient creature with whom your main character can converse, perhaps argue or, better yet, engage in some action. If a person is out and doing, it’s more likely that something interesting might happen to her or him. Shut up in a room with only his thoughts for company well, that way lies fictional disaster.