Love what I do Versus I have to do it

How much should we like what we do?
Is just affinity enough? Is the rest taken care of by obligations and people who impose those on us?
How do we know who makes the obligations? Isn't it us who oblige ourselves to do or not to do a certain action? Do we not set the goals and limits ourselves?

The most important aspect of our doing what we want to do is determining what we want to do. And this is extremely difficult when you come out of a society, group or environment that influences your thinking and your choices. Examples of such environments are smaller towns, where people tend to live in a closer community, and thus influence each other more in terms of views, judgements, etc. Such environments emerge in a much more complex array of circumstances than just the location and presence of a small residential area.
Now we will take a person out of such an environment and put him in an open community. He will not be forced to believe, think or do anything, but will be subject to many ideals and opinions. To what extent will such a person be affected by the environment? Will he accept the ideals of others? Will he preserve his identity?

This, however, does not answer the question in the beginning - how do we know what we want to do, but it limits the array of answers by aiming at false ideals. Such ideals can be easily created and raised to the heights of immortal virtues in groups where people are vulnerable to outside influence.