I don't think you should seek to be "emotionless." The key to being cool is that you are not affected by your environment and what other people do. You have to understand that your emotional state depends on YOU.
No one MAKES you angry or sad. You are the one who chooses to feel those emotions. Yes, early on it can be tough, but if you keep reminding yourself of this fact, you will learn to be in control of your emotions. Don't allow other people to dictate your emotional state. If you allow that to happen, you lose.
Next time you begin to feel sad because it didn't work out. Remind yourself that it is you who is choosing to feel that way. Use your logic to overwhelm your emotion. The first few times, it will be difficult. But with practice, you will eliminate destructive thought patterns and emotional states.