From my limited but growing experience in therapy I have observed that there is one underlying factor that affects how people behave, think, and feel. Now, this one factor does not discount the effects of other factors but it is a prevalent theme in the lives of many of the people I have worked with in therapy. This factor is what is called self-centeredness, or in other words, 
selfishness. Any time that people focus on themselves, they cannot focus on those around them. Some people are able to focus on themselves but then switch over to an outward focus. Others are not very good at this. The problem with focusing on oneself is that when external events occur, their effects are all driven inwardly and change is effected in the individual. Over time some people develop dependencies on external stimuli to the extent of exclusion or occlusion of internal, self-driven stimuli. This is what is called an external locus of control. I am not discounting people who have what psychologists call an internal locus of control, which is often viewed as a more positive, internally driven sense of control over life, but the majority of people I have seen in therapy emphasized external events to an extreme extent. That is, they let external events control their lives and thus their emotions, thoughts, and behaviors.
My interpretation of why this occurs in some people is that everything external becomes internalized (i.e., everything outside themselves gets focused inward). If something bad happens at work (the external event), a person might twist it into a reflection of her sense of the worth of her inner self. This means that something negative (even if it was that person’s fault) becomes a reflection of that person’s character rather than simply a negative event (e.g., “I am a failure” versus “I sure made a mistake there!” – notice the difference between the negative self-evaluation and the labeling of a negative event). This is an attack to a person’s sense of self worth; this attack on the self can turn into a vicious cycle of self-defeating blows. Attributing negative events to one’s character is a form of self-centeredness. However, that is only part of the self-centeredness of which I am writing. what I mean by self-centeredness goes beyond locus of control – it is an attitudinal and personal characteristic of interpreting everything as being about oneself. This is not narcissistic personality disorder – it’s not an overt and extreme ‘personality’ characteristic, it’s a learned way of interpreting events. It is relatively mild and probably not even noticeable to many other people (narcissism is obvious) and almost never to the individual.
This selfishness is manifest in the perpetual worrying of the state of the Self instead of the Other. This does not mean that the self-centered one never worries about other people, it means that they are never able to ‘forget’ themselves. I believe that true happiness comes only by forgetting oneself and serving others. One problem with this belief is that some will misunderstand it and spend all their time doing thing for others at the expense of their needs – but that is rare. But one can, on average, spend the bulk of his or her time focused on others instead of on oneself. From my completely anecdotal personal experience, those people who spend the least amount of time thinking about themselves are usually the happiest. The corollary to this is that those who spend the most amount of time thinking about themselves are usually the least happy.
We all make choices. Choice – free will – is not an illusion. We all choose how we react in life – to our thoughts, to our boss, to a spouse, to others. Dr. Barbara Heise stated, “We give up our…right to choose when we say, ‘He (or she) made me angry.’ I encourage you not to give away your right to choose by handing that power over to someone else. No one can ‘make’ you angry. You make a choice to respond by being angry or by taking offense. But you can also choose to make the effort to find out what is really going on with the other person and understand their behavior—or maybe just agree to disagree.” (Source).
We are agents of our actions. We choose our attitudes and most of our thoughts. Every person on earth faces hardships of one kind or another. Some might face starvation or abuse or loss of loved ones. Some might face loneliness or addiction or stress. Some people might face anxiety or depression. But here is the key – we can choose what our attitude will be; we can choose to be happy or sad. Yes, even in depression. The choice of happiness does not mean that we are happy all the time or happy immediately, it means that we will try to respond with happiness throughout our day; it means we will work toward the goal of happiness. I know that most people would say that happiness (as opposed to unhappiness) is always a goal for them but how many people are actively choosing happiness.
The surest way to overcome unhappiness, or even anxiety or a number of other common mental health problems, is by choosing to forget the self and get to work, so to speak. We can choose to be self-centered or we can choose to be other-centered. This choice and action of other-centeredness is the surest way to happiness and peace. That is the intriguing thing about focusing on others – and I mean really focusing on others; I’ve met people who spend most of their time filling the needs and wants of others and who are unhappy; why are they unhappy? They are unhappy because they resented the time spent for others. Many times this resentment was not overt but it was obvious in their speech. But if we are able to truly focus outward towards others, we will find that our self takes care of itself. We get anxious because we are worried about what others think of ourselves. We feel depressed for much the same manner – focusing inward on the self – and interpreting many external events through the lens of the self. That is not necessarily bad when external events are positive but when they are negative, it can lead to depression.
When I was young, my younger brother would on occasion do something that I found annoying. When I protested to my father, he usually replied, “Don’t be annoyed.” That lesson stuck. It does not mean I never again felt annoyed – I do from time to time – but it helped me realize that being annoyed is a choice. What one person might find annoying, another person will not. I do not believe that most people, when they do something others find annoying, are meaning to be annoying; most simply do not realize that they are doing something other people might find annoying. A gentle request that they stop will often solve the problem. Again, the choice is there – choose to not be annoyed. In the same manner, choose to be happy.
I do not mean to minimize the complexities of depression or anxiety but I do not think that we should give away our choice of happiness by allowing others or our biology or other stressors to determine our happiness. I have to admit that I do not believe in determinism, I do not think it exists. If we learn anything from quantum physics it is that there is some level of indeterminacy to basic matter. By extrapolation, this means that even a small uncertainty might affect larger entities, such as neurotransmitters or neurons, or pathways, or beings. Indeterminacy does not equal free will or choice but it is a component of it. I do not believe we should let anything hold our happiness hostage. True happiness comes from focusing on others – note that they are not determining your happiness, you are choosing to focus outwardly and happiness results; not because you are seeking it but because when you focus on others, when you serve others, happiness finds you. You open the door to it and let it in to your life. The choice is there – you can choose to be self-centered and miserable or you can choose to be other-centered and happy. What do you choose?