It’s an interesting question that can be answered multiple ways leading to different outcomes. Let’s take a look.
…Because this is how it has always been done. Honest answer when given. For a few, you believe in it so much that you are able to bring energy and enthusiasm to what you are doing. For most others, this answer is the polite way of telling someone that they have never really thought about the question. They just go through each day as it comes with few worries.
…Because what we are doing isn’t working. A person feels trapped when responding this way. The obstacles or the breakdowns they are experiencing are frustrating. But they are responsible enough to know that they have to try to do something different. While this is quite noble, what tends to be missing in their answer is the lack of patience to spend more time trying to understand why things are not working before trying something different.
…Because others are counting on me to do this. Another response that implies feeling trapped. Where you feel you have to do something because you do not want to disappoint others. Holiday decorating is an example. This type of answer implies that some unseen pressure is placed on you that keeps you from doing something different or not at all. There is a fear that others would not think as highly of you if you did nothing or that they do not have the interest to adjust and fill the void you have now created.
…Because I was told to. This answer is the ultimate “pass the buck” response. It communicates that you don’t care if it works or not and are totally disengaged from the context or reason as to why it was necessary to do what you were told to do.
...Because I am trying to accomplish a specific thing. Makes the person who said this seem thoughtful and conscientious. That they have thought through what is worth working towards. The risk in the confidence implied in this answer is whether or not what you were working towards fits the overall direction you intend on pursuing. It also suggests that what you are trying to do is what you believe is the best and/or only way to accomplish that specific thing.
…Because I need to find out if I am “on the right track”. This has a different feel to it where the uncertainty of the outcome becomes the purpose for doing something. Where you need to learn if you are on the right track. Where if you fail, you do not get stuck but understand you need to adjust and try again. Hidden in this answer is a sense of direction where you are trying to accomplish something but will reserve judgment as to the best way to achieve it until you test further.
…I don’t know why. Habits that become unconscious routines or behaviors can be identified when someone answers in this way. Pushing us into one of the other possible answers above is a great first step to becoming more self-aware of things we unconsciously do without thinking.
How we answer this simple question “why are we doing this?” is a great window into how we think and reminds us why we sometimes mess up when we limit ourselves to only one answer without ever considering that many are possible.