Most people think it does and they believe external factors do influence our state of emotions and are responsible for changes in our moods. If it is the fact then let us consider few more situations. When you have an awful day and things look quite bad, does an action like watching some comedy, reading jokes etc change our mood? Do we start feeling better? Always? May be not. Remember like incidents and you will agree that sometimes external factors do not at all change our basic state of emotions. Take another example. You are happy and enjoying and then out of nowhere something bad happens. You may be playing football and then suddenly it starts raining. But, instead of getting irritated you change your action and start doing something else and continue your good emotional state.
So, what does it mean? Is it that external factors are really that important and influential on your basic emotional state or not? Some believe this is a very subjective issue and the causality of external factors on state of emotions of a person can not be determined in way that could make it a rule. There are so many things to consider - intensity of prevailing emotion, importance of external factor(s), basic psychology of the subject etc. If the prevailing emotion is intense enough and external factor is not that big an issue in terms of importance, then the subject may not have his emotional state affected at all. If external factor is big enough and basic state of emotion of the subject is weak, then he may be affected more. Also, a person who is by nature cheerful, may not be affected easily by those events that may be 'irritating' to others.
Well, this may be true that influence of external factors on a person's emotional state are subjective and depend on various things, but, there is a lot more to it. It all depends on our mental toughness, the trait which separates 'weaker' people from 'stronger' ones. Someone who is mentally tough is not affected by external events so easily. This is something that was developed through evolution of memes which follows the basic idea of 'survival of the fittest'. Those who are mentally tough find it easier to cope with difficult circumstances and through natural selection, their genes have stronger chances of survival.
It is actually tough to be mentally tough. Do you also think so? I think its a feedback cycle kind of thing - if we are tough enough then chances are we don't find it tough enough to be mentally tough. Oppositely, if we are weak enough then chances are we find it tough enough to be mentally tough. So this cycle goes on in this way. Its our perception that needs to change, we need to believe first that we can be mentally tough and this perception will change our ability to better our basic psychology. Attitude is basically what matters and if we have right attitude we can become stronger individuals who are not easily influenced by external factors. The causality of external factors to change our prevailing emotional state is established only if we are mentally weak, otherwise, we are not influenced by external factors.