On staring out at a gloomy day: First you must realize that it is the day that is gloomy, not you. If you want to be gloomy, too, that's all right, but it's not mandatory.
On staring out at a gloomy day: First you must realize that it is the day that is gloomy, not you. If you want to be gloomy, too, that's all right, but it's not mandatory.