I believe it could affect our trade but we don't have to let this emotion as a reason why we fail to decide right. The more we are happy, means we are very comfortable with our doings and even more motivated to do so. Because what I mostly observed is that those people who think negatively and are unhappy usually got in big trouble and eventually lose more control of their emotions leading to losing funds.
Besides, we don't need to stop everything and feel nothing. We can still have those emotions (positive and negative) but of course, the most important is we know how to manage ourselves when it comes to making a decision.
I think "happy" and excited are different things. If you are happy that will go on a bit longer and that means you are happy with what's happening and that's not a problem. However, if you are excited that doesn't mean that it is just happy, it also means that you are overjoyed and acting about it as well, happy is a state of mind, excited is a response to something.
I would guess that trading while excited may not give good results, it could in fact hurt you more than it helps you and that's why it should not be a good thing to do. I rather do something much better by ending up at a great result in the long run and just focus on profiting when I am calmer.