You said trading is a part of business , afaik every business needs emotion like for example you need to be happy so that your costumers or employees will also feel the same but if you are sad do you think your costumer will back to you  ?  And do you think your employees wont be afraid to you if they see that you are always in a bad mood ? I guess not .

That can also happen in trading because trading is also a business .  we need to be positive and smile even though we loose sometimes so that we can still be motivated to try again .  its also okay to feel sad and cry if you loose because that can cleanse your body and soul .