Its all too easy to forget that there is one person controlling how we choose to interact with the world. You. You choose whether you will be knocked down or lifted up by events outside of your personal reality. You decide if you're going to allow the stop light cheater to alter your mood.
You. Not anyone else. You.
You are the lens by which the world enters your perceptions. You are the mechanism that translates events into good or bad, the events themselves simply are, they have no morals, they have no sense of value save what is placed upon them by human perceptions.
If you are having a bad day then you can choose not to. It really is as simple as that. Choose. Decide. Alter. Change.
If someone asks you how your day is going and you reply "Terrible" then maybe you should consider why you are choosing to have a terrible day. There are events that can upset one's day, the operative word being "can". You choose to allow them to ruin your day or you do not. When you have a bad day, you choose to have a bad day based on your reactions to outside events.